Hi there, I'm also new here, I came over from J-Novel Club Nina. I love, and I mean really LOVE romantasy novels, but I also really enjoy reading the occasional isekai and transported into a game world novel. And I think JNC's novels are especially good in terms of quality and translation. They are also published regularly, so you don't have to wait endlessly for the next volume, which can be quite annoying.
Anyway, I could recommend you:
-Ascendance of a Bookworm (literally one of the best light novels I‘ve ever read)
-Bibliophile Princess
-Dahlia in Bloom: Crafting a Fresh Start with Magical Tools
-Deathbound Duke‘s Daughter (though it got unfortunately axed after the second volume)
-Earl and Fairy (a bit old-fashioned, but otherwise quite good if you like fairies)
-Goodbye, Overtime! This Reincarnated Villainess Is Living for Her New Big Brother (more about familial love than a real romance, but it‘s a really cozy read)
-Tearmoon Empire (it‘s a really funny and well written story)
-The Apothecary Diaries (not really a romance novel, but with a very interesting main character and a very well written (mystery) story
-The Tales of Marielle Clarac
I hope this helps. There are many wonderful novels from J-Novel Club.