"Where is company located?" - well, formally in Poland, but server-wise it's all Google so what should I say here? Or it doesn't matter when it's all offline?
And just for the record, I really appreciate your valuable inputs!
I'd definitely mention Poland, since "made in EU" is a big bonus for everyone in the EU (both for privacy and for billing/payments). If the data isn't uploaded, the servers don't matter for that part. They're relevant regarding you user's personal data (e.g. their IP), but if their CSV doesn't touch the server, that's ideal from a privacy perspective. You'll still need to put your use of Google into your privacy information, but that's a formality and very few people (especially in a company setting) care about their own PII being stored on your server - it's other peoples' PII that they get in trouble for.
At least for enterprise customers, you might also need to be more transparent about yourself, i.e. "Who's offering this service". You'll need to have it for billing anyways, and will also require it in your privacy notice ("who's responsible, who can I contact about my data").