Europa Stamps on Postcards.

I inherited a lot of European CEPT stamps (1966–2024) from my grandmother. There are lots of duplicates from abroad (for example, 5x Poland 2022).

I used to think that if I sent a Polish stamp, my postcard would automatically get a Polish ID. But no. The postcard is sent from Germany, so it gets a German ID. Got it. :D

Now the big question is:
Can I go into Travel Mode, set my location to Poland, and send a postcard with the Polish stamp from Germany? (I know that I also need German stamps to actual send a card). I even have Polish postcards. The "only thing" that would really be wrong would be the German postmark and the additional German stamps.

Or is this generally not desirable and I should only send German stamps from Germany? That would be super sad, because there are already so many stamps from Germany and I have really cool stamps from Azerbaijan, Poland, the Isle of Man, Portugal and Switzerland that I would love to share, but I'm not there soon on vacation to send them from there.

Tipto, good afternoon and Merry Christmas!
I'm NOT the administrator, so my answer is purely my opinion, obviously.
The ideal would be to pre-select Poland, the Polish Europa stamp, and go to Poland to post the postcards ;-)
If you can't go to Poland, I think it's best to leave Germany as the Country and select the correct Polish Europa stamp (obviously, you'll also have to pay the German postage rate).
If they are ' old ' Europa stamps, they may not already be listed. In that case, you'll have to carefully update the catalog yourself; beware of duplicates!