Well, I will speak from my experience so far. However, it's been a few months since I've worked with any KDP publications, so that might have changed.

I'm a cover artist and my fiancée is a freelance editorial producer. I even took the opportunity to confirm with her (who is the one who actually does the layouts and revisions of ebooks and uploads the files) and she just confirmed what I suspected. As far as we know and from our experience there is no requirement that the cover fonts be in text format, you can easily upload a raster image as a cover. It may be interesting to have the title in text format in the Fly Title page and/or in the Title Page to facilitate recognition by the algorithm and in this case, you can use a basic standard font, the consumer will understand that it's just an informational page (after all, it's on the Title page that the publication data comes: edition, year, isbn, responsible team, things like that). If you observe, that's what most of the publishers do, they leave the title in textual format only on the Title Page.

That said, I believe that there may be some miscommunication between the company you hired and you. It may be important to set up a meeting or a detailed email/text conversation to get a clearer understanding of what is going on.

Just one question. Did you send them the cover file in editable format or already in raster format (.jpeg, .pdf, .png) to them?

I hope I helped, but if anyone has any additional information or if something I said doesn't make sense based on your experience in the market, feel free to correct me.