Isn't "connard" a sort of swearword, more like "dickwad"? I always thought it was...

We French are as rude as you can be in Russia, just less drunk...

Point was, is it appropriate to translate a non-swearword, "moron", as a swearword, "connard", since even though they can be close the latter seems to have far worse implications?

Then you missed the meaning of my initial answer : Yes, we French (at least among my circles) would frequently use « connard » to translate « moron » in the same context.
"moron" is quite offensive. It doesn't equate with a simple "idiot", as you might think. It implies that the person is mentally retarded. [fra]« idiot » is far more affectionate and wouldn't fit in this context, I think.
To express the same level of offense, « connard » is one of the options in French.
It doesn't mean that the person is retarded but that he/she behaves really foolishly.
Belgian francophones would consider it ruder than I do, and wouldn't use it at all, actually, and there are probably other social and regional nuances within France. But « connard » is current in Paris, for instance. It can even be used kind of affectionately among friends, such as : « T'es vraiment un connard » to mean "You're such an idiot".

There's a permanent inflation movement, in French, especially in Paris, but also in the South (Marseille, Toulouse, ...), to use the worst swearwords excessively, then these swearwords come progressively to be considered less rude because of their permanence and then even ruder words have to be found to serve as really rude swearwords instead.

For example, « Putain » is quite rude if you think of it and translate it literally, but most (young but also less young ) French use it almost in any sentence.
If I lose my keys, I will normally say « Putain, j'ai perdu mes clés », even though no whore is involved in the process.

The same goes with « Con » (which literally means "cunt". And if I had uttered it in hearing distance of my grandmother, she would have slapped me) but that people in southern France use almost every three words to actually mean nothing...I also say it (although less than Southerners) to mean "stupid" (« C'est con » = "How stupid"). It certainly is considered much less rude nowadays than it was during my childhood.

So my answer was actually a serious one : French tend to favour and apply literally ruder words than Usians would, for what I know. But it must depend on communities.
I often go to London, and I hear the same inflationary phenomenon there, although it's difficult for a non-native to really perceive the rudeness level of swearwords.

People probably tend to be ruder in capital-cities (my own French is a Paris one, even though I wasn't born there, but that is were I studied and where I spent the longest time so far), because people in capitals tend to snub provincial people through shocking them a bit.
In France, I think there is an additional phenomenon of North vs South capitals competition, because people from Marseille are also very rude.

Maybe you can confirm that this phenomenon also takes place in Moscow...

Here, I heard "Don't be a moron." in the movie "Nebraska" (excellent movie, by the way), and that was said by an old very outspoken man, to his son.
I frankly see myself saying the equivalent this way in French to my own son.
But again, other French people, from other backgrounds, regions or age would not use it. I definitely would.

Sorry for the long answer but if that's what it takes...

Actually, you don't have to be sorry at all, it was a very interesting answer and quite the kind of answer that I like most - I find these explanations to be very useful to understand things on a theoretical level, and I'm the type to seek theoretical understanding in addition to practical aptitude.

Of course, I understand now what you mean. It is indeed a very common phenomenon, but since as you correctly pointed out it's difficult for a non-native to grasp the exact connotations of a swearword and my knowledge of French swearwords is quite basic, I didn't really give it thought, I admit.

It's quite fascinating how swearing varies between regions. Should serve as a good reminder to be careful (in any language) with using strong words in 'real life' even though after seeing a lot of texts on the Web taking swearing casually one may adopt the same attitude but it always depends on where you go.

I myself was raised to take swearing rather seriously. A lot of people take it easier, of course, but I think the devaluing that you spoke of only goes up to a certain level because there are no ruder words than what we already have (Russian мат) so if they get much too common and consequently mild there will be no strong enough words left to convey an aching emotion.

to tell you how far this goes, young French people, nowadays, sometimes casually call each other « enculé de ta race ! » which literally means "screwed one from your race", which manages to join racialism to sexual prejudice. A very ugly prowess. I never created this one on Tatoeba because I don't say it myself. But you hear it all the time in Paris, for anything...

Sky is the limit...