Is there a way to bulk import schedule actuals or overrides?

Yes! By default, Planner will create a schedule using the assumptions set up in an asset template and lookup tables. If you need to override duration values in order to capture actuals or updated forecasts, you can use the Excel import to do that in bulk. Details can be found here:

https://planner-help.pod2.tech/articles/129830-excel-integration-importing-dates-activity-actuals