Go ahead and report it to the Mint team. Even if it is an issue upstream, they will verify the issue and then report it as well. Never hesitate to report a bug you find, especially if it’s a security or privacy issue.
Even if the bug is a duplicate, it helps to know other people are having the same issue. At worst they will mark your report as a duplicate, which will let you know they are aware of the issue.
I’m a vim user and I would say it’s not. It’s very powerful, but only once you become familiar with the commands.
Nano is a better default for the average user because it works in a way most users would expect for a text editor to work.