I'd like to know as well.
It's probably because of cultural difference, though. In Japan, you can only call someone their first name if you're close and it would be really rude to call them by first name if you've just met. I'm guessing they find calling people other than their names isn't as romantic as calling their first name (and maybe even rude).
Well we have authors that love to create tons of foreign semes and all that so I was a little bit surprise that there are so few to none that use terms of endearment, especially when a BL manga is set outside Japan. ╮(￣▽￣)╭
tbh japanese people love nicknames but pet names really aren't a thing. i'm thinking of the ones that i've read and sometimes and i mean sometimes you'll see them use darling but that was in english to begin with and i feel like it's kind of a joke to them.
try looking for those in webcomics not in mangas
and I recommend the website tapastic, they have a load of bl and the authors are from all around the world, so some may use those nicknames. Hope this helps :PP
Hola, Putas! I can't really recall any BL manga that I've read with the seme using terms of endearment. to the uke. Seriously are there BL manga out there with seme calling the uke "babe" or "honey" or "love"? Idk about you but it's such a huge turn on for me lmao