AFCI Breaker Randomly Tripping - No New Devices
AFCIs work by literally listening to the power line for the telltale sound of arcing. This is why they are new developments, it requires signal processing power akin to that seen in The Hunt for Red October. 

The relevant thing is AFCIs can hear arc faults nearby on other circuits. So your arc fault may not be on the protected circuit.  However a circuit cannot arc fault if its breaker is off.  So if you can stand to have a circuit off for awhile, you can test whether it is the cause (or is not).

AFCIs were developed to protect from electric blanket fires, but mainly ended up detecting failed "backstab" wire connections.  Backstabs are a cheap and fast method to attach wires to receptacles and switches. A tiny spring of metal clamps the wire, causing localized heating.  Pushing everything into the box puts strain forces on the wire which makes the contact area even smaller than designed.  

Most modern houses are full of them.  Most of us here on diy.se have experienced them failing in scary and melty ways. Screw terminals don't do that as a rule, especially if properly torqued. So as a process of elimination, I would first get rid of all backstab connections on that circuit.  

As for the kitchen circuit, Code requires that circuits powering kitchen countertop receptacles, power only them. So that circuit should go straight from the panel to the kitchen and nowhere else.  If that doesn't go anywhere near your recent work, we can exclude that.