Can an Indonesian spouse of an American on a retirement visa in Thailand stay long-term without having to renew every 30 days?

Yes. They can piggy back as a dependent until they are 50, then they need their own.

Sadly there's no way a spouse of a foreigner on a "retirement visa" (Non-O visa/extension) can get a Non-O visa based on "trailing spouse", not from an embassy outside the country and not from the immigration office inside the country.

There is no limit to the number of visa exempt entries that Indonesian people can get by air or land, and since July 15th 2024 the free entry stamp (visa exempt) went from 30 days to 60 days and they can get one 30 day extension on it at the immigration office for 1900baht