Rzeczpospolita translation?

Both as a literal translation

Not really - it's a direct calque of the Latin Res Publica.

Still, no one talks of the Roman Commonwealth. Why?

Res = thing, object
Publica = public, common

The word rzeczpospolita doesn's seem to come even close to the Latin res publica.

Erm, it's an exact(ish) word-for-word substitution, no?

My point is that the word rzeczpospolita and commonwealth seem to be a much better, more accurate match. After all there's the term republika in Polish too, correct?

Erm, it's an exact(ish) word-for-word substitution, no?

They also choose other weird expressions like voivod and marshal, as if they all have exuberant handlebar moustaches and rides around on horseback wielding sabres and lances

Should we apologize for our rich history and traditions, too? Or at least be little bit ashamed of it?

Its you who is weird.

There is a word "republika" in Polish, but it's only used for foreign countries
(Republika Czeska, Chińska Republika Ludowa etc.) or, as a general term,
for a form of government. "Rzeczpospolita" is used almost exclusively for
Poland (occasionally you may see the word used in historical context i.e.
"Rzeczpospolita Rzymska" or "Rzeczpospolita Wenecka".)

So, in other words, there are many republikas in the world, but there
is only one Rzeczpospolita. Such is the contemporary usage anyway.
It would sound quite unusual if someone spoke of "Rzeczpospolita Czeska"
or "Chińska Rzeczpospolita Ludowa".

Bzi, you've completely missed the point. Varsovian is having a bit of a laugh at the expense of almost, but not quite well informed foreigners' views of Poland - not the actual history as it was.

My point is that the word rzeczpospolita and commonwealth seem to be a much better, more accurate match.

Your instinct is good, much better than Poles on PF:)
pospolita - means in this context - common

For example the Polish-Lithuanian Union was called the Commonwealth of Poland & Lithuania in the English speaking world.

Well, I haven't been in Poland for decades but I'm in touch with many family members who travel to Poland several times a year, so I'm not as ignorant of Rzeczpospolita III as you'd think.

Russian controlled "respublika" plague even more

I think they should've used Rzeczpospolita for the Polish speaking population and Commonwealth for the English speaking world, why do they have to use the same term everyone else is using?

Poland is definitely NOT a commonwealth

a commonwealth is an allied group of republics

Well, Poland is not a republic either !

Ustrój polityczny Rzeczypospolitej Polskiej (Trzeciej Rzeczypospolitej[1]) określony jest
Konstytucją Rzeczypospolitej Polskiej uchwaloną przez Zgromadzenie Narodowe 2 kwietnia
1997 roku. Zgodnie z jej treścią Rzeczpospolita Polska jest republiką parlamentarną.

Yes, it is - according to Polish constitution.

However Rzeczpospolita is not republic, we have a name for republic.

End of.

The term of commonwealth is right as a way of convening the meaning of term Rzeczpospolita.

Yes, the name Rzeczpospolita derives from respublica

Well, Poland is not a republic either !

Yes, the name Rzeczpospolita derives from respublica but conveys quite different meaning
of the content - Rzeczpospolita was so unique at the time

aysus, Iron. Rzeczpospolita is essentially just another word for Republika - accept it.

Now, get over it ;)

However I think that essentially this term should be used to describe historical RP, we have term republika in the language for a reason.