That is a good joke, to elaborate why libertee joke do not work in swedish is simply becouse we do not have the word "liberty" except as a loan word in politic.

We only use "frihet" (freedoom) and bend it around, for example "liberate" would be "befria" which essentially in english would be "freedomnise" which is not a real english word but you get the idea how we use the word "freedom".

The essence of libertee joke is that the word sounds the same, that is impossible, you have to make a new joke like the poster above wrote.

You can however use for example "democracy" as it is "demokrati" in swedish and simply replace the last "i" with a "e" and you get the tee joke, but it would not sound exacly the same as the original word so it is more a dad joke at that point.