I feel like Rakan's "Xayah Bonus" should be on his Q instead of his E.
With the current system, it doesn't feel like you are getting "Double Range" when targeting a Xayah.
It feels like you are getting gypped out of your escape when you are targeting anyone else.
So, here's my suggestion.
First, change his E to be the same range versus all champions. This range would be halfway between the current "Xayah Range" and "Other Range". Because Rakan still wants to protect his lovebird, the range would be extended to live values when targeting a Xayah with low health.
Second, change his Q to give Xayah a healing circle when Rakan lands Q. It's more in line with what Xayah gives to Rakan, it doesn't feel like you are missing out when you aren't with Xayah, and it encourages the couple to get closer.