FVEY memo has a line expressly guaranteeing that all partners' surveillance/privacy laws will be respected as if they were their own. There is no loophole in the FVEY agreement, nor is such a thing regularly practiced. Speaking as someone with mil experience in NSA, if a Canadian citizen or resident, or a selector that reasonably pointed to Canada, came up in comms, we would treat it exactly like a US person and disregard unless it had FI value, in which case it's punted back to Canada to make a decision on warrant before anything is done with (mirroring the process that FBI would get involved with a FISA authorization on anything involving US persons rather than us unilaterally saying collect is justified). On top of that, yeah, expressly searching on Canadian selectors would not happen unless CSE already had their own warrant authorization and passed that to us... so legally, they wouldn't

What Snowden leaked regarding anglosphere collect/reporting were one-off exceptions to FVEY Agreement (or collection agreements separate from FVEY) and not the norm. Trying to mind bias here, but can fairly say he left the context of many legal safeguards out of his leaks. FVEY primary purpose is just to maximize coverage on Ru+Ch and (nowadays) in cyber, as each nation brought alot of unique collect and expertise on those targets.