I will try in English too
You got me right and this was exactly what I tried first - to adjust the general template of "Il_crs_admin" or "_il_grp_admin". But somehow it doesn't work in the way I expected it. If I change the rights in the template, it doesn't effect the already automatically local produced "crs admins" which can be up to 300 and I have to adjust every one of them manually.
I tried to create a global role of "Teacher" but then if I changed the rights afterwards it wasn't transmitted to all courses / groups in the same way - although I set the hook to transmit the rights to all existing objects. Maybe this means only real objects as categories but not groups or courses?
I probably missed something important or did it wrong but after days of trying I just don't find the mistake.