Ah! I got to the point where high repetition learners concept was introduced. Doing everything in doubles, triples and quadruples sounds about right. Didn’t quite feel the barrier at the first several challenges, because i was habitually doing stuff in triples from the start, but i think blue belt is a place where I hit the ceiling of what I can pick up without some more creative crutches than just doing doubles, triples and quadruples.
I’d add faulty phonemic awareness to the list of possible underlying factors. Faulty phonemic awareness compromises auditory memory in turn. Introducing words one by one more or less works, introducing them in sets of three in old challenges does not, by the time I hear third word the interference of second and third kills any recollection of the first, reintroducing the first interferes with the third and I end up retaining nothing.
My guess is, blue belt has too many tense patterns at once at the point where I’m not quite confident in present, they end up interfering with each other and de-automatizing barely automatized present. I had to slow down considerably, got to blue-white, it’s manageable, but I’m painfully slow and I have to consciously think about every single pattern, including most basic like dw i.
Possibly that also explains why Irish phonetics became an issue. Takes hellish amount of time to tune into different set of phonemes, I need an explanation of what I’m supposed to hear to actually hear and process it, and if what I hear doesn’t match what I should hear, I end up disoriented.
It’s very common for this to happen at least once during the course. Experience has shown that people who push on, and accept that learning is taking place at a subconscious level so they’re not yet aware of it, then after advancing for a while come back and run through again, are often surprised by how much easier it is, and by how much they can suddenly produce.
As a little aside, I knew a couple who were learning Welsh with us in Aberystwyth. They were both at different stages, so they were studying in different rooms before heading out for the evening. As they were leaving, they were both telling the other how hard their session had been and how they didn’t remember anything from it and they would definitely have to do it again.
That evening they were in a bar where they had a chance to speak Welsh, and to their great surprise, they found themselves using words and expressions from the sessions they had just had and didn’t think they remembered! It can happen! 
That sounds cool. Problem is, core feature of autistic spectrum is that things do not naturally get absorbed, at least not that effective, unless they are verbal and explicit. Basically why we are so terrible at social rules. Which means every time I hear something like “you’ll just pick it up naturally/subconsciously/whatever” I ask myself if I actually have hardware that is supposed to do that (usually not). Dysgucymraeg definitely makes thing easier, but there’s a gap between grammar explained there and grammar at SaySomething, where I need analytical understanding to rely on, but don’t have it yet. Suppose should get easier when I finish Mynediad, but I’m not even in the middle of it yet and I’ll need a second run on Mynediad curriculum anyway. I use a system where I do first run for passive skills for several months, then the same stuff again, but with writing and actually pronouncing words. With Welsh I’m experimenting with early output. As I said, it’s interesting, but it’s not what I would normally do and I acutely feel my limits. “Normal dizziness” mentioned elsewhere sent me to bed for a few days, I nearly fell down a few times when I was adapting to early speaking. Regular brain architecture would probably be better equipped, but I don’t have one. So it’s an interesting task of finding compromise between following methodology and adapting it to the hardware I actually have.
To get some taste of how bad my hardware is at everything that’s not written text, I only stopped getting sensory overload from walking down the street last year, when I methodically worked through university textbook on architecture and manually taught my visual cortex to decode houses into spatial structures instead of just choking on them. Face recognition is still not online, and I’m nearly forty. I could probably manually build it too if I worked through a textbook on forensic art, but facial features are just not as interesting as Celtic languages 
I’m mostly telling this because course content told me to go and mention the difficulties on forum. As I understand, it was meant to be a request for support, but I’m used to finding solutions on my own and standard solutions rarely work on me anyway. Documenting the process might have some value though, for later similar cases.
Thank you so much for sharing this. It’s important for all of us to try to see the world through other people’s eyes, and it’s something I’m always working on. So getting this glimpse into understanding how you are processing everything is so helpful. I don’t know how/if it will help the development of the course (not my responsibility!) but from a personal perspective it is so enlightening.
While there’s no official reading material to go along with SSi, since you’re needing explanations that neither SSi nor more formal courses have, I highly recommend Gareth King’s books. He has written many excellent books going over different aspects of the language either broadly or in more detail. What I think might be best for you right now is Colloquial Welsh. This one is a coursebook very much focused on Welsh as really spoken rather than the idealised forms most teachers may prefer. It covers a lot of varieties so it still won’t all correspond to what’s taught on SSi, but it is likely to be a lot more applicable than the standard Dysgu Cymraeg materials in ways you could find useful.
And of course, always ask on the forum if you don’t understand something. I’m doing Uwch right now, and more than once I’ve known something others on the course didn’t, because it came up in the Challenges and I read some questions and answers about it right here.
Ah! Diolch yn fawr, I’ll check it.
I was just about to suggest Gareth King’s Colloquial Welsh too, as it’s excellent.
Depending how much you like to see grammar laid out in simple tables, you might find https://clwbmalucachu.co.uk/ useful. I’ve got a fair number of verbnoun conjugations all laid out, and am still moving stuff over from the old HTML site. But if you find that useful then it’ll be worth buying BBC’s Learn Welsh book, which is basically just tables of stuff.
Diolch! Colloquial Welsh seems pretty close to Teach Yourself format I’m used to, it does seem a good fit.
I usually end up doing my own tables, keeping parallel dictionaries of Gaelics and Welsh helps to keep track of what’s similar and what’s not. Compared to Irish Welsh feels incredibly humane, actually. At least what you see is more or less what you hear and words don’t have twice as many letters as they have sounds which don’t even correspond to the letters 
Incidentally there’s a terrific movie about linguistic frustration, “Arrival” (2016), aliens talk in sounds, but write in circles which have zero correlation to the sounds. “God Almighty, how do I make sense of it” situation.
Love that movie!
I also love this movie!
I hear you! Think I went at it the wrong way around…