Incomplete universal character name in UI Testing
You can use the following workaround as this seems to be a bug in xcode:
replace all \U to \u and it should work.
I tried replace \U to \u but still got error "Expected hexadecimal code in braces after unicode escape", so have to add \u{you value here}, like collectionViewsQuery.buttons["\u{6ce8}\u{518c}"].tap()
See more at Expected hexadecimal code in braces after unicode escape