In regards to Elise, the main issue is the fact that while she and Rean
, they were still raised as siblings from a very young age, so it comes across as awkward that she would be able to see him as anything else.
So were Estelle and Joshua though.
I think what bothers people is that Elise is very much imouto trope played straight for the most part. At least in CS1. On top of Onii-Chan honorifics in the original, their relationship seems very one sided, with there not being much to Elise beyond pining for her brother's affection.
I think the only thing that bothers me with both personally is how openly accepting and encouraging outside parties seem to be towards both pairings.
I was fine with Estelle and Joshua's relationship by the end of the game after becoming familiar with the nature of their relationship, but when their childhood friends and Schera tease Estelle about it in chapter one I was sort of left scratching my head, to the point where early on I was rooting against their relationship becoming romantic lol.
My reaction to Elise is the same. I was sort of ok with Alfin's teasing as she's the sister of you know who, but then I read the translation of the Drama CD and uhhhhhhhhhh...
Again, I can't go into this in detail because of the Crossbell arc, but there are more reasons to think it's not to avoid spoilers than to think it is. And if you really like to know, scroll up to preta's post and reveal a major spoiler for yourself.
Nah I trust your Kiseki expertise. I'll wait until I can experience those games.