It seems that placeholders can only be used in the Player entity. In my case, I want to use the condition of clicking on an element and then identifying it, but I can't because I can only work with placeholders.

You need to explain that better, dude 😅
I don't understand that bug report, sorry lmao

So currently, it is not possible to do the following: When clicking on the player entity and moving the mouse, the Player entity should rotate as the mouse moves.

Sure, no problem. So I wanted to use the “when clicking on an element” requirement in the advanced mode rotation of the Player entity, but currently the advanced mode only supports placeholders.

The rotation is a value. You can't use requirements in values of any kind.
You are supposed to check with a Ticker if the element is hovered and let the Ticker set a variable you can then get as placeholder in the rotation value. For example, you could use the Switch Case placeholder and let it return a fixed rotation as long as the element is not hovered and if it is hovered, let it return your rotation logic.

If you have more questions about that, please join my Discord.