adding from discord channel:

Would it be possible to only track the current legion IDs instead of all IDs? I run pretty much all raids (new and old ones) with only one character and because of this character the list gets super long and blocks the whole screen pretty much. So if I could only track legion IDs i would have a better overview for my alts.

at this time there's not an easy way to do this yet. Blizzard only returns the expansion for 1 of the api's but not the other unfortunately.