The Polish minority in Lithuania is autochtone, as far as I know (unlike Cyrillic in Germany). Furthermore, it's not merely a matter of not using the Polish letters - as the link that I provided says, their names get Lithuanized. (Mickiewicz > Mickevičius)
Since I assume you're Serbian (your handle + the mention of ć and Cyrillic), here's an example.
Imagine that the Hungarians in North of Serbia weren't allowed to write their name as Szabo Lajos (or Lajos Szabo) and instead they were forced to use Lajoš Sabić.
> Imagine that the Hungarians in North of Serbia weren't allowed to write their name as Szabo Lajos (or Lajos Szabo) and instead they were forced to use Lajoš Sabić.
You are absolutely right here. I was speaking only about an alphabet part of the problems, and why it is not practical. Forcing someone else to "translate" the name is completely other problem, which is much more severe. There is certainly a difference between writing István as Ištvan simply because it's how it's pronounced and the lack of á in alphabet and forcing him to call himself Ivan (or Stefan).
There are many offenders to this, like Greece, or Bulgaria, or China, which IIRC at one moment required its own citizens to have "westernized" names in their travel documents.
Since I assume you're Serbian (your handle + the mention of ć and Cyrillic), here's an example.
Imagine that the Hungarians in North of Serbia weren't allowed to write their name as Szabo Lajos (or Lajos Szabo) and instead they were forced to use Lajoš Sabić.