Buodd/bu - same thing. Only difference is habit in terms of where they get used - ‘bu bron iddi’ is much more common than ‘buodd bron iddi’, for example, same with ‘bu farw’ instead of ‘buodd farw’.
Fill your boots here:
https://en.wikibooks.org/wiki/Welsh/Verbs
In case it helps to satisfy the desire to understand what’s going on, I’d probably gloss bu / bron / iddi word-for-word as “it was / almost / that she”. So bu bron iddi anghofio, “it was almost that she forgot”, i.e. “she almost forgot”.
But of course ultimately this bu bron i is just a handy often-used pattern that you’ll just get used to hearing. It’s encountered with other subjects too, e.g. bu bron i mi, bu bron i’r sefyllfa, bu bron i Siôn Corn etc. 
Listen up gogs, it’s lessonin’ time! Challenge 17 is now out!
Iestyn and Cat have been playing an excellent game of catch-up lately, but Aran and Catrin are just and so pulling ahead once again…
(This one isn’t available on the app yet at time of writing, but will be very soon… and you can always get it on the website 
)
[Update: Jeff tells me he’s now updated it onto the app too. Amdani!]
…aaaand here’s Challenge 18! Available now from a website or app near you.
Hwre. Just before i go to bed 
I’ll do it tomorrow!
Either the challenges are getting easier or I’ve picked up some Welsh somewhere. I was saying allwedd instead of goriadau (or I’ve watched Ben Dant far too much), now I don’t know which one to use…
Both allwedd and goriad, agoriad are in common use, as far as I know! Take your pick
I think (a)goriad is more common in the north.
I know, I assumed goriad was more Northern, I have been doing the Northern course after all. It’s just that I picked up allwedd already, so I feel I have a choice which to use. When these choices happen I’m tending to pick whichever I prefer the sound of. Does anyone else have this issue?
Yeah, I do too. Emma’s cousins and mam use goriad, I’d always said allwedd. The list of these sorts of things is endless.
Which is exactly the right thing to do…
Challenge 19 is out on the website today It should be on the app soon.
And indeedy it is …
Ok, so now, finally, at last I can do the long sentences! All i had to do was learn enough Welsh so I could devote all my attention to remembering what to say, rather than how to say it. I have achieved something.
Diolch , much appreciated
Fy ymynedd wedi toddi unwaith eto. Hwre! My brain has melted again, Huzzah!
why do I find level 3 easy but the old course 3 is soooo difficult.
I found that as well. Perhaps easy is an exaggeration, but easier. I’m guessing that for the last few challenges we are widening our grasp of the structures that we already have. Also, to be fair, we have had the pain already in the “old” course.
However, I can’t help thinking that we might be coasting towards storm 25
I’ve got to say that I am loving the new words. I need to combine the equivalents of the likes of
Serious? Really? If I could only trust you, etc into a grumpy old man recording
'Cause it wasn’t written very well… 