I have installed MySQL 5.6 on Ubuntu trusty, I successfully added this instance remotely, but Engine value for this instance on PMM list page is displayed as (Ubuntu). Maybe it's because of 'Server version: 5.6.33-0ubuntu0.14.04.1 (Ubuntu)' ..
I think it should be MySQL in this case
And there I another problem: Requirements say that Engine column should display not only type of DB server, but version too, for example mysql "v5.7.19"
Another problem I've found that Engine dqplayes PostgreSQL, but mysql and aurora. I think it's better to use the similar format for all types.