Having lived in Abertawe in the 90s, I can ‘slush’ my ll, breath my rh, but - as a Northern English lad - I cannot properly strangle my ch. Ychydig is agony, dechrae is slightly easier! But…does it matter?
It’ll come with practice! For ‘ychydig’, I’d suggest trying saying yc-hydig and getting faster and faster at saying yc-hydig, and after a while the ch will appear. This tip won’t work with every word because surrounding letters will make it difficult but when the ch is between two vowels, this tip does seem to work.
In some words, especially when they’re spoken quickly, the ch can sound like a c anyway, so don’t worry too much - as long as you never pronounce it like ‘church’, you’ll be ok
Can you say loch and Sasannach in Scottish? Or, perhaps the Scouse or Irish -ck which sounds like -ch?
Bizarrely can get it when saying Chwaer or Chwarae but it is elsewhere it disappears. Loch is no better BTW.
Ah right. Possibly because they are at the start of the words, giving you a run up. I find the mid or end word sounds more tricky, but easier if I slow down and speak more gently not trying to blurt them out in a panic.