in my experience there might be a few people for whom "the icons are different, i need a training course" is a legitimate concern. but for the vast majority of workers, it's not "i need a training course" it's "i feel like i can get away with demanding a training course" with the full knowledge that asking for a training course will derail the effort to make a change.
Yeah, there are people who think that they are being paid to be at work, not to do work, to apply themselves, to engage, to provide and produce. And it sucks to work with those kinds of people.
Then a coworker showed an even more sophisticated version of the same joke. He created a nearly identical relationship but he would look for job offers matching their resume and pitch them. Look, this is closer to where you live and the pay is better!
Stick to conventions, don't reinvent the wheel, and training needs should be minimal.
Very few people who know MS Office could not pick up LibreOffice and be fine with it.