- Or we could invent something more simple, a slang, cant, cryptolect or jargon.
The French are great creators of those, though French itself makes it quite easy to play with words compared with other languages. Largonji, louchébem and javanais are the most important ones. Largonji and louchébem are similar: replace the first letter of the word with an "l", and either speak it at the end or add an "em" sound after it.
"Jargon" becomes in largonji: l-argon-j
''"Boucher""' (butcher in French) becomes in louchébem: l-oucher-b-em
The name itself highlights how it works. Short words are skipped, and words starting with a vowel just get an "l" and generally end in "much". It works wonders in French, now let's see how well you lunderstoodmuch the leviousprem lexplanationmuch, and letherwhem you can lunderstandmuch the lollowingfem in louchébem, and now the lurrent-c lentence-s in largon-g. Doesn't work as well as it does in French, but you get the drift. Javanais is simpler, just add "av" everywhere, savo thave favolavowaving saventavence gavets ravealavy vahard tavo unavderavstand.
It's quite simple in fact, your brain quickly gets used to it, but for someone who doesn't get it, it just sounds like complete gibberish, and it's even more confusing considering it kinda sounds like the actual language, but in a form that cannot be understood. Such techniques have been used at many points in history to great effect. The great thing is that you actually need to practice it actively to use it and understand it, so you couldn't just learn the technique from someone and expect it to work. Even when the secret is revealed, most people still won't get it. If we were to form a group of practitioners of such a jargon, it would almost be like a new language.
And honestly, a slang seems more than enough. We don't need an extra language for our everyday lives, we only need to identify each other, exchange quick words, ideas others cannot hear. I guess that's it. At most, you could learn a language of your choice properly, if you want to show true commitment and not just pass as a shill who learned how to say Demat, or learn the classics (Latin, Greek, French) so you can tap into the greatest books of all time in their original language. The rest is LARPing territory.
When it comes to the outside, we need to speak as many languages as possible, spread our ideas for a better Evropa in ways people can understand them, and have people join us: English, Spanish, Italian, Portuguese, German, Swedish, Russian, Polish… because maintaining a hermetic sikrit klub mentality with an obscure language will only lead to a death of it on the inside.
We're not all the same. The whiteness of our skin, and the christian values we share, unite us. But when it comes to the rest, we're different people. Europe is one of the most culturally diverse places on the whole planet. Better focus on things we actually share, than try to shoehorn some sort of homogeneity, because we all know where forced equality leads.
Because a language is much more than it implies, there's a culture coming with it, a way of thinking, specific values. You're not changing that, so don't expect to change the languages.