It only half shows it. I think it might show the penalty on the offer screen but not when you actually open up the offer. I think it only shows your new cap. They need to put the penalty in parenthesis on that screen or something. I'm not for sure it even shows the full penalty on the offer screen I'll check.
I didn't even know about trades and the cap penalty personally until I did franchise in M11. I always thought it was just the team owed them a portion of their salary for the season they cut them. It should probably say what it is you're actually adding to the penalty. It should probably this players X$$ signing bonus will count against your salary cap next season. Like I said I thought it was either a portion of their salary or what was listed as cap salary that was actually counting against until that M11 franchise.
To earlier point on players wanting more than they say, most of the time they end up singing for what's listed as their contract when you pull them up in non-franchise mode. Why don't they just put that down as their desired contract when you sign them during the main season? Also, players never resign for less or a change in the bonus/overall ratio like they do in real life. Players don't ask for less after digressing, being cut, or stats going down.
What about resigning players you already have whose contract is not up? When I go to the screen to submit an offer it shows my cap space as if I'm paying both contracts. Am I still paying the old singing bonus plus the new contract?