Not really a tag I follow, so I don’t have a strong opinion either way. Delusion and Daydream already sounds quite different to me in English yet they are used as interchangeably on StashDB.
All I can add is this: There are two different tags on DMM/FANZA 妄想 (Daydream) and 妄想族 (Daydreamers). The translations in parentheses are “official” insofar as they are from R18.com but it’s not like there was never a poor translation on that site during its run.