Note: Finally found information, that it's not possible at a normal language school. If it is, you can approve this, if not just delete it. Thank you!
Does somebody here have experience with the approval when applying at a language school in the country with an ED 1 year visa while on amnesty?
TLDR : Answer Summary
The consensus among users is that language schools in Thailand do not provide visas or extensions of stay, particularly in the context of applying for an ED visa while under amnesty. Immigration authorities require that applicants have valid days of stay remaining on their current visa.