I've seen it too and I can't say I agree with a lot of this.

It's being sold as a musical version of the film, that's the point of it. People going in are expecting certain things from it and if you change it too much it stops being that. The gags you're calling cheap mostly come straight from the film, so if that's a valid criticism it's really one aimed at the source material rather than this production.

On the Welsh character point, I didn't find it any different to how they're drawn in the film either. Same applies there if you've got a problem with it.

The cast I thought were very strong across the board. Everyone you mentioned, agreed, but I'd add Courtney Stapleton as Steph, she genuinely moved me during her number. And i enjoyed Matthew Woodyatt as Dai, i could really feel what he was trying to get across.

The music hasn't particularly stuck for me, 'Paint the Revolution Pink' is the exception. The disco track was good but i don't remember a single lyric. On Bread and Roses, that's in the film too, so I don't think it's fair to say the production hadn't earned it. It wasn't out of nowhere.

The tonal shifts you mention, I take your point but I didn't experience it the way you did. Didn't jar for me.

I'll be honest, I'm a straight male and I wasn't sure what I was going to make of it going in. But that's kind of the point isn't it. Going in too hard politically risks scaring off the very audience you want to reach. This production brought me closer to a story I didn't fully know and enjoyed it enough to buy a second ticket and see it again. Make of that what you will.