Is there a way to switch existing local Infuse data to a different iCloud account without any data loss?
Apple doesn’t allow data to transfer between iCloud accounts.
However, if you have local data in Infuse on a particular device, and then sign into a different iCloud account (that does not already have Infuse data) that data should sync from the device to iCloud.
Note: This isn’t a process we have tested extensively, so YMMV.