Yea, take a look for yourself. Just rename those files to wc9 and drag into PKHeX. If they are a Pokémon gift, they’ll load just fine.
and as for why some of them aren’t there, not all gifts are permanently in the BCAT. Once the event expires, the team that manages BCAT may choose to remove them.
And IIRC your device’s BCAT tends to sync with the server whenever you’re idle in your HOME screen connected to the network, or when you grab a new network gift, so your old archives would have been gone.
Anyhow, this won’t work fully for the Switch Gift Data Manager (since it’ll need data from your own BCAT; you can merge the relevant files you want into your BCAT, as per instructions in SGDM), but @CitrusBolt has been dumping them: https://citrusbolt.net/bcat/
Lastly, we have an event repository that has all the events we gathered (all of Gen 9 is there): https://github.com/projectpokemon/EventsGallery
And finally finally, this isn’t the right place to have this discussion. Please start your own thread in the Events Help and Questions sub-forum if you need more help.