I don’t know about that. There is such a thing as the Ukrainian language. And there is a Belarusian language. So I think it can be fairly argued that neither country is a made-up one.
Now, should each country exist as an independent nation? That’s a whole other subject.
Yes.
The usage of Ukrainian language is now rising.
After the Russian invasion, everybody n Ukraine started to speak Ukrainian.
That invasion really defined Ukraine as a nation!
However Belarusian language is now suppressed.
The dictator Lukashenko wants to get rid of it!
There is no such a language as Moldovan.
Just some minor dialect differences within Romanian.
Stalin wanted more land to grab, so he grabbed Moldova from Romania during WWII.
Russian and Ukrainian are only about 60% mutually comprehensible.
Belarussian and Russian are about 75% mutually comprehensible.
Moldovan and Romanian are 99% mutually comprehensible.
Moldova is a chunk of Romania grabbed by the USSR in 1944.
Just like Northern Macedonia is really a chunk of Bulgaria