I wish we didn't even have a registry like that. Our nicest enemies are better than our meaner friends, so of course you only hear about it when someone wants to score propaganda points.
Iranian-Canadians have been asking the Liberal government of Canada to do this countless times, especially in recent years and following the shooting down of Ukrainian flight PS752 by the Islamic Revolutionary Guard Corps (IRGC) in January 2020. So far, sadly, the government has ignored the calls. Perhaps a foreign government can put pressure on them!
If the criteria for declaring a state military organization as terrorists, is abuses of international humanitarian convention and the rules of war, then the Revolutionary Guard can pop onto the list along with the IDF. And a bunch of others really. Calling groups and people terrorists is pretty popular these days, but the word actually has a legitimate use, which isn't to ratify Israeli acts of war against other sovereign nations. Even if, like Israel, those nations are run by shit heads.