Most keyboards... and beige PC plastics in general... are made of ABS plastic (or ABS + PS and possibly HB for flamability-compliance.)
So in regards to that (or more specifically keyboard #5) any PVC or ABS plastics glue should work fine to glue the broken parts.
I usually use PVC pipe glue because I always have some and it always works great. Just put it on both broken pieces, wait for the plastic to soften up a little from the glue, and then put the parts together. Leave to dry for minimum of 24 hours without disturbance and 1 week for full strength.
In regards to the rubber dome keyboard (#4?): did you wash it without removing the plastic trace sheets? These usually don't deal well with moisture or water, so I never wash these. If very dirty, I might wipe them with 90% IPA, but that's it. Now, if this keyboard uses a design where the rubber domes also integrate the carbon contacts, you'll probably want to wash these too with water+dish soap (do NOT use any other aggressive cleaning agents.)
I know it's just a rubber dome keyboard, but honestly I prefer those over the other "mechanicals", especially any modern stuff (which I call "fake mechanicals" for reasons I'd rather not rant about here.)
As for keyboard #1: I imagine the broken keys can be glued back with some hot glue. Same for keyboard #2... unless those keycap parts happen to be made from ABS or PS plastic as well - in which case, use PVC glue as mentioned above. (Note: if unsure about a plastic type, you can use PVC glue to tell. Apply a small drop onto an inconspicuous area and see if the plastics becomes "melty" or "goo-ey" when scratched with a small screwdriver after a minute of the glue sitting on it. If yes, it's probably ABS, PS, or other similar plastic that reacts to solvent glues. If not, then solvent-based glues won't work very well with it.)
