Your transaction issues shouldn’t be a Sheets versus Excel issue. The downloading of bank data takes place before Tiller knows whether it’s going to fill in Google or Microsoft. It also shouldn’t be a timing issue. Those sequencing issues may affect when something downloads within a 24-48 hour window, but they shouldn’t explain a week-long delay. I think you need to give customer support a chance to sort this one out.
As for categories and tags, I think you’re referring to the conversation about third-level categorization in a thread a couple of weeks ago. You could use Utilities:Electricity as a category, and then, say, Home and Beach House as tags to distinguish between properties. That would allow you easily to see how much you were spending on electricity at your Beach House (by filtering to Utilities:Electricity as a category and Beach House as a tag), but also how much you are spending in total across categories at your Beach House (by filtering to Beach House as a tag). You could also use something like Transaction Tracker to facilitate that filtering.