Ignoring the real world reasons for Glossaryck’s voice actor changing, I think it would be at the very least really amusing if in-universe his voice changed every single time he “died” or otherwise went MIA for a while.

Like, an example from before Ludo burned up the Book of Spells in current canon would be when the fire happened during Skywynne’s Wand Passing Ceremony that burned up the castle and first Magic Book of Spells. When he came back from that his voice was also different (presumably what it is at the beginning of the show)

In current canon, if magic were to come back and Glossaryck along with it, his voice would be different as well.

When he travels through time I imagine his voice is whatever his voice he currently has (i.e. in Meteora’s Lesson his voice is Keith David and not whatever Glossaryck’s voice actually was back then) instead of reverting back.

I just find it a mighty funny idea that l might play with in my AU