"We are having lots of fun in Switzerland."
Translation:Meillä on tosi hauskaa Sveitsissä.
"Paljon" cannot really modify "hauskaa." You could say "Siellä on paljon hauskaa tekemistä" where "paljon" modifies "hauskaa tekemistä" (fun things to do), but since "hauska" is an adjective, not a noun like "fun" in "lots of fun", it doesn't work with "paljon" on its own.
If you wanted to use something other than "tosi" or "todella", you could use e.g. "erittäin" (extremely), but it does sound more formal. "Hurjan hauskaa" could be translated as "terribly fun". In spoken Finnish people also use e.g. "sairaan hauskaa" (sairas - sick) and "sikahauskaa" (sika - pig) to convey the same thing.
This is helpful. I made the same assumption (paljon). So what you're saying is that while "fun" in English is both a noun and adjective (in same spelling) in the Finnish context here it is purely an adjective? Say we use English "jolly" instead which can only be an adjective, it's better to read it as "we have very jolly", or, most literally, "on we/us is very jolly"? That's an odd-sounding grammar to an English ear if so, but fine, logical enough, makes sense, just a different way of doing thing. But just want to check I've got this noun vs adjective distinction correct...
Actually it is the same in English. The word "very" can mean express intensity (e.g. very big) but comes from the same root as verily / verify / veritas all talking about "truth". Also "really" as an intensifier, from "real" which is again about authenticity i.e. truth. It's not surprising in any language; an emphasis on the truth of a statement ("that's not true" / "It is so"), can easily become an intensifier ("I am so tired", meaning not just that you aren't lying about being tired, but your tiredness is substantial).
Whenever there's a new construction in Finnish (or any language) that doesn't fit what I'm used to, what helps me is to find another way of expressing the idea in English (my native language) that's closer to the way the idea is expressed in Finnish.
For this sentence, I conceptualize it as something like "It is really fun for us in Switzerland" which expresses the same idea, but is closer to the way the sentence is constructed in Finnish.
In English "really fun" can mean "actually fun" (as opposed to that being a false claim), or intensively fun. Really can be both about truth (it's really me) and degree (a really big car). So we are really having fun in switzerland has two meanings in english; that as a matter of fact we are having fun (in case you thought i was lying) or that the fun we are having is intense. Similar to the two senses you've now met with tosi