I've had my CX4 for about four years now and while I like it a lot it's trigger could be a bit lighter and also every once in a while it feels like it doesn't reset on a follow up shot.

Are there any fixed for this or aftermarket parts that could correct this?

You can buy the parts to do the trigger at the link I have added below. The people who have done this upgrade are pleased with it. I have avoided it for years as my CX-4 is one of six PCC's I have and after the DIY trigger job I was OK with the trigger. The trigger is NOT as good as a good AR trigger and never will be. However, after the DIY job its OK for most. I have used mine for years with the home brew trigger job without issue. Its a ten minute job. There is a lot of information out there for anyone who makes the effort to do the search for "Beretta Storm CX-4 DIY trigger job".

I will attach a link for you to one discussion of this, there are many more available. You have to do the search yourself after this however.....

DIY CX-4 trigger job discussion with some diagrams

Replacement trigger for CX-4

Custom made metal trigger parts for CX-4

I did the DIY trigger mod, it can be done without disassembling the trigger so you can file just a bit at a time.
Just smoothes and lightens the trigger, but great results for zero cost and 15 minutes of your time.

Sierra Papa is the only source for trigger upgrades I'm aware of.

I followed a step by step from the Beretta Owners forum, it had a drawing of the hammer sear and showed the maximum you can safely take off. I did a little less than that, if you take too much off your Storm won't fire (or will be unsafe).