Okay, so I wanted to post another video by this guy, which deals with German, but this one kind of seems to summarize the points I want better: https://youtu.be/61Kk7VkoWbc It's about Latin, and if that immediately turns you off, in short he emphasizes the idea that mastery of a language is directly proportional to the amount of exposure to it... And also has little to do with its quality. Which, on the one hand, goes against your approach of trying to understand everything your book presents, but also against mine of surmounting one sentence every day... He also repeatedly recommends reading bilingual texts, which...

Well, I suppose I know where to get some bilingual texts in Welsh, for free. But...

No, of course he's right. I suppose my current method is like his deconstructing of Latin grammar... Sigh, how I yearn back to the simpler times of starting to learn Polish, when I had a perfect goal and materials. Quite frankly, deconstructing Welsh grammar has simply been more appealing than actually reading anything in the language.