Hey Brian,
Welcome and thank you for posting. At this time, the best way to make changes to imported events using Events Aggregator > Google Calendars is to make the changes needed to the series of events on Google Calendar, then reimport them into your site. Before doing so, make sure you have the settings correct under your Events > Settings > Imports tab. (see screenshot below)

We have a feature ticket logged which will achieve what you’re ultimately asking for, but until then I unfortunately don’t have another solution. Thanks again and please let me know if this helps answer your question. Cheers!