This breaks the resource for non-custom roles as the naming is different. read vs pull, write vs push etc.

I'm seeing the same as @csainty. Confusingly, around half of the repositories we manage seem to use "push" and the other half "write". It could look like the oldest repositories we have wants to use "push", so I'm guessing it might have something to do with when the repository is created.

Not having it mapped to the same name makes it difficult to use for_each to assign a list of repositories to a group with the correct permissions.

Same here. This is a breaking change for use. If we keep it as is some 300 repos will be changed on every run, if we change push to write, some 450 repos will be changed every run.

We should revert or create some option to have aliases or something.

If somebody finds a way to "rename" the roles in Github, please share. That might be a solution as well.

For us some of the differences seem to come from roles/permissions assigned to groups (teams), org members (collaborators) and outside collaborators.

That seems to be the difference between in the v3 api:

https://api.github.com/repos/<org>/<repo>/teams
https://api.github.com/repos/<org>/<repo>/collaborators (works only for org members)
https://api.github.com/repos/<org>/<repo>/collaborators/<user>/permission (works for outside collaborators)

Note that https://api.github.com/repos/<org>/<repo>/collaborators/<user> doesn't return anything for outside collaborators.

(fyi we only use the default roles)

Some information here https://github.community/t/is-the-api-insane-with-respect-to-collaborators-or-am-i-confused/253696

Created a new ticket in #1222 as comments here might get unnoticed.