I'm running Monterey 12.5.1 on a late 2013 iMac (iMac14,2) using OpenCore Legacy Patcher. This model should only be able to run the latest version of Catalina hence the need to use OCLP. Using SilentKnight suggests that the EFI firmware needs updating. My understanding is that it relates to a recent Security Update 2022-005 Catalina, which came out after I had already updated to Monterey. My questions are:
Does it matter?
And if it does should I try to update the firmware by booting into Catalina from an external drive (if that's doable)?
From personal experience & from what I can gather from Eclectic Light [the maker of SilentKnight] firmware upgrades are done as part of an OS install, or upgrade.
I don't think simply booting from Catalina will do it, You'll need to install or update Catalina whilst booted from it.
This was certainly true for Mojave, which I was part of the beta test for. Every single beta update had you re-applying the firmware update again, whether it needed it or not.
I managed to get the firmware to update to the latest for my iMac model. I made my computer dual bootable into either Monterey or Catalina. Set my startup disc to Catalina, restarted but with a NVRAM reset (after something I read on the MacRumours forum), then reapplied the latest Catalina security update and the EFI version updated.
I was able to also use the above procedure to update my MacBook Pro 9,2 from 233 to 429 by installing Catalina and the latest security updated on my second internal SSD drive. I have 2 SSDs in this MacBook Pro and I have Ventura with OCLP installed on one drive. I installed Catalina to the second drive. I did the CMD-OPT-P-R NVRAM reset then installed the latest security update to get the update.
I updated a MacMini 2012 6,2 from 422 to 429 EFI as well by loading Catalina and the latest security update and performing a OPT-CMD-P-R NVRAM reset. This also runs OCLP.