If that matches the CAPF.pem from the publisher that signed all of your LSCs, you'll need to regenerate the CAPF certificate, restart CAPF service, re-run the CTL client, and then do a CAPF Install/Upgrade on all phones to push out new LSCs in bulk signed by the new CAPF certificate. Once that is all done, you can delete the old CallManager-trust certificates for the expired CAPF certificate.
You can visit most phones' web pages via HTTPS and check what cert is shown in the browser to see which certificate signed the LSC on each phone. There's tools out there to do this kind of thing in bulk.
If the CAPF certificate that signed the phones' LSCs expires and the phones have a security profile configured, they will fail to re-register if they reset for any reason. If they don't reset, they'll be fine forever but it's a ticking time-bomb situation. Extension Mobility environments are affected immediately since every login/logout resets the phones.
I'd suggest opening a TAC case under the CUCM Security/CTL sub-technology keyword so that they can take a look at your specific situation.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...