Its hard coded not to exceed 60 fps.  It isn't adjustable.  The reason for this is that players notice varying frame rates a lot more than slower frame rates.  If we didn't clamp a max on it then sometimes you would get 90fps and other times you would get 70.  That variance looks really flaky (worse than running 70fps all the time).

Determining what number we clamp to has pros and cons.  The higher it is the better it looks, but the more risk you have for variance.  So we try to lock to a reasonable number that we can provide on a reasonable system on a reliable basis.  We don't tend to let players opt to higher stats since on 90% of players computers that will make the game perform worse.

Some players assume that since high poly fixed field games like battlefield and tomb raider can deliver higher fps on more detailed objects that their computer should be capable of doing that with high object count world view games like Fallen Enchantress.  Unfortunately its much harder to display worlds where the player can scan from one corner to the other over hundreds of different objects and units.  Where players tend to think about the amount of detail filling their monitor as a fixed amount (beautiful picture that measures 24"x16") or that graphics difficulty is correlated to the quality of the individual assets they are seeing (that is certainly a factor, though its still easier to show one high poly detailed unit over 10 lower poly seperately animated and modeled units).  And the fixed field game have a huge advantage of knowing about what the player will see next, so they only have to have a small area prepared at any one time (which is why jumping across the map in skyrim or other games invovles load times).  In world view games you can jump anywhere at any time, so the whole game is prepared to display at once.  Hard on memory, hard on the gpu.

Anyway, the whole point of the above paragraph (besides being something we think about a lot here at Stardock) is to say that even if we put in an option for 120Hz this isn't the kind of game it work well on.

can we somhow check ourselves how bad is it?

You don't even need 60 FPS for this game, really.  I've got it capped at 17 FPS (which I've found to be the lowest you can set it to before it becomes hard to look at).  Can't imagine why you'd want to run it at 120 Hz.  I mean, you could do stereoscopic 3D, but why?  This isn't the sort of game you'd want that for.