In the US, those are regulated. I'm not aware of the details, but I doubt these "certificates" in Poland have the same level of regulation as US securities.

This merely makes these certificates worth less than the same but named stock options and regulated.

The employee will "just" need to discount the value of these certificates accordingly.

It would also be weird if managers were to capriciously hand out options to employees as short term performance bonuses.

Weird, normal-and-accepted, guess it depends what part of the industry you work in.

You've piqued my curiosity - where is this normal and accepted?

Normally at tech companies there’s a review and bonus twice a year. At ours we only participate in one of them, the other is done by management, and for most of my career ours would just pretend he decided to give us a bonus for our hard work one day. You had to ask around and notice it was always the same week to figure out how it worked.