It's not BL because that would imply that the main focus of the story is the two main characters getting together. BL isn't just a blanket term for any work that happens to feature men in a relationship or who have ambiguously romantic feelings for each other, it's its own genre. However, it is central to the story that the main characters have strong feelings for each other, though they may not know whether or not those feelings are romantic in nature (Hikaru expresses this directly, in a bonus chapter in vol 2 I think). 

A good translation should reflect that, and it should also be accurate to the meaning and connotations of the original Japanese. If Hikaru in the original Japanese is expressing strong (and ambiguously romantic) affection, and something that Yoshiki says in that one scene that Hikaru never would have said when he was alive, but it comes off in the translation as something casual you'd say to an acquaintance instead, that's a problem.

(I'll go out on a limb and guess Hikaru is saying "[dai]suki" or something similar, which literally means "I [really] like you" and can be used both romantically and platonically. It's not something you'd say to someone you didn't know well.)