How are you exporting your excel spreadsheets? I see you mentioned UTF-8 in the title but sadly didn’t elaborate on that. I remember trying to do import from excel ages ago and found it pretty much impossible to get UTF-8 encoded csvs from Excel.
Personally, I found that libreoffice is pretty straightforward in it’s export UI. So maybe try that one.
- Open your xlsx in libreoffice
- Export as csv/tsv (maybe look at encodings on Windows? On Linux it’s straightforward)
- Import csv/tsv into Anki.
I hope that libreoffice is the same on Windows. I haven’t used it on that platform.