I think it's fit since the context of Reflection in the mirror in the main story is from Ginko-chan's grandma song since before School Idol Club established there was Performing Arts Club which Ginko-chan's grandma belong to that club and eventually the lyrics itself has pass down through generation until the school idol club created so it does makes sense for the slower version of Reflection in the mirror
When first I heard 103 ver. I thought it was meh, but this 104 remix is 100 times better imo.Also after listening this and then going to lisen 103 it thought to myself:Is this nighcore version? lol