Actually, a lot more than one person has been charged, and some were convicted. As of July of 2019, almost a dozed people have actually been sentenced.
https://www.kunc.org/2019-07-17/six-years-in-few-people-have-been-sentenced-under-colorados-large-capacity-magazine-ban#stream/0
Charges and prosecutions take place, the latest being just a few months ago:
https://kdvr.com/news/problem-solvers/former-vail-government-employee-accused-of-embezzling-854k/
Another recent case involves an arrest during one of the many protests and counter-protests during the summer in downtown Denver. At least one person was charged with a magazine related offense, but the news article at the time did not specify whether that was an alleged violation of state or Denver laws.
The OP's question was "how illegal am I?" in the context of bringing 30-rd magazines and a "shorty pistol" into CO. The answer is "illegal for several reasons". Colorado State imposes a 15-rd limit while exempting magazines that were already in the state prior to a certain date. Some jurisdictions have their own, more strict limits. Denver, for example has a 15-rd limit that does not exempt any previously legal magazines.
In addition to the issues of magazines, the OP's "shorty pistol", which I assume is an SBR-like AR, will also run afoul of local Assault Weapon bans. Denver and Boulder have these bans that are easy to look up on the internet. One of the questions I'd consider is how is the OP getting to CO. If the OP is flying into DIA, then he shouldn't assume that Denver's firearm laws aren't enforced there by Denver PD.