the 1.0 schematics are here
there are no major changes to 1.2 (afaik) only minor changes related to power protection (see posts on early issues), but I'm pretty sure these won't make any difference to end users.
perhaps @Johannes you could add a copy of the revised 1.2 schematics to the above page.
i don't see any of your posts being unanswered, which posts are you referring too? what open questions do you have?
I'm not really into the hardware side myself, so probably cant help much, but, there are a lot of people here that are very helpful with lots of experience, and have done a amazing number of different things with axoloti.
so id recommend asking questions here, perhaps someone can help you.