I want to be able to disable seasons in specific dimensions and maybe even configure the season length per dimension.

Seasons are supposed to be overworld-only. Maybe also for overworld-like dimensions, but certainly not for nether or end, or similar "alien" dimensions.

I don't know why I kept overlooking this issue. But I noticed this has been solved way back in d6bb686. So I'm closing this issue, as it shouldn't be relevant anymore.