The え sound is actually a poor indicator, unless you know its verb pair.
When paired with a verb that rhymes with ある, the verb that rhymes with える is transitive.
For example:
始める (はじめる) is transitive
始まる (はじまる) is intransitive
When paired with a verb that ends in す, the verb that rhymes with える is intransitive.
For example:
返す (かえす) is transitive
返る (かえる) is intransitive
I don’t apply it unless I already know the pair and it actually works, so its more for reinforcing what I already know. I wouldn’t just use it randomly in the wild.
I’ll take a look and see if there’s a better way though.
Apologies for the reply. When I first read what you wrote it came off as a little bit aggressive, but that’s written communication for you. No harm done, and tbh I did get that part wrong.