Can I use Arial in my sheets?

[Petie]

For reference, it would have been fine to leave the Arial font in. Technically, it’s owned and copyrighted but copyright on fonts is a little weird. If you own any Microsoft product, like Office or even Windows, the license granted by owning that product also grants you the use of the Arial font in commercial works, if I’m understanding this correctly.

But more importantly, your work is not commercial in nature here regardless so you should be good either way.