Checking for Program Change events (PC) opening each regions in the Event list takes time to my opinion.
I may offer a fast batch "Destructive" deletion or "Non-Destructive" temporary hiding/clutching the PCs.
1. Destructive delation.
Select all problem regions in the Arrange (in my scenario I hit Cmd+A cause all regions are imported from SMF) and create a Transform Window setting or Template shown in (Fig.1) below. Hit - "Select & Operate" button which will batch delete all PCs of the all regions in one step.
2. Non-Destructive delation - PC Clutching ON.
In this scenario/template (Fig.2) all PCs are transformed to "neutral" messages (Meta Event 0 ...)
3. Non-Destructive recalling - PC Clutching OFF.
In this scenario/template (Fig.3) all transformed/clutched PCs are transformed back to PC in case if you need them.
Another scenario of filtering is to create a Multi Instrument or Standard Instrument in the Environment (a Multi is automatically created or all Midi File regions are placed on its tracks when import any Midi File for example).
1. Add a new Transformer object and set it to "Filter Matching events" - Status -> Program. Cable the transformer from the Multi.
2. Create a new Channel Splitter object and cable it from the Transformer in the chain.
2. Cable the Channel Splitter pins to the Software Instruments you want (it does not matter if they are set to ch.All or any channels cause we use a Direct cabling in this scenario).