Am I too late to lay may thoughts on this? (I probably am). Eh, I’ll say it anyways.
I’m not in the know, but I think when they meant by the 2014 rule is that all of the characters they have so far haven’t been created past 2014.
I think it was in response to the “shill character” where the person said that the “promotional” character couldn’t be someone brand new because they didn’t heard anyone that was created past 2014, and the “promotional” character was later heavily suggested to be Yuri, which was heard already, and most likely wasn’t even meant to be a promotional character since Tales of Vapseria just so happened to also be coming to Switch as well and is apparently competing with another character.
So I think it may be possible that a character from after-2014 could potentially appear later on. We only seem to know information on 2 characters, but not the other 3.
Though I would appreciate it if someone came out and stated if it that was the case.