Hey,
my forges have now a standard-quality of 100%.
Is this intentional?

Can you explain further? Does this mean you're seeing a +100% quality modifier on the Forge? If so this is incorrect/a bug. Can you clarify if this is just a tooltip issue or if the rate is actually applied? Are you using any other mods that might be impacting quality? Lastly, what setting do you have for the "buffed forge" option? If buffed forge is ON, the forge's normal 10% quality boost (from the original mod) is reduced to +0%, while the productivity and crafting speed are increased. Neither setting should result in a native +100% quality boost.

Now, I tested it. Only Factorio SA + Castra installed, buffed forge off: the forge has +100 Quality.

I'll be honest, as they seem to be continuing to introduce breaking changes in the modding API, I'm inclined to wait until 2.1 is a stable release to tackle these issues.

Initial review: it looks like they have changed the math on how these mods work.

effect_receiver = { base_effect = { productivity = 0.25, quality = 1 } },

This line is where Castra defines what I'm pretty sure used to be a 10% quality boost. I've looked and it's the same line in the original mod.

This time with the unstable version is wild. You can put it on the to-do-list and wait until it is release. 😉

Yeah they are breaking all mods for every major (minor) update for now, so I guess is easier to wait full release