Maybe I'll try the manhwa

Hmm, probably start with a part of the side story?
One side story is about the time Josh presented as an omega. If you only read that one you won't be spoiled on the main story, but probably get more interested in Josh. So it's easier to get into the main story. They are on wattpad, only read the first three parts (one day).
But it could also be the translation. If you haven't tried this one https://wordexcerpt.com/series/kiss-me-if-you-can/ try it, but only the first 7 chapters are free and it's incomplete. The translation is better, so you would at least know if the translation is the reason you were unable to continue.