Polish grammar requries surnames ending in -ko such as Kościuszko to be decliend like feminine nouns:
ACC Kościuszkę, etc.
And yet former finance minister Kołodko remained undeclined: misję powierzono ministrowi Kołodko.
Anyone knwo why? Has this chnaged, and if so -- when? If one writes to someone about an Andrzej Siemiaszko or Leon Bojko should one write: Już poinformowałem pana Siemiaszkę or Siemiaszko, życzyłem profesorowi Bojce or Bojko (if one does not know his particular preference)? Can one correctly write: Naród zaufał Tadeuszowi Kościuszko?
The rule and the norm in the Polish language is generally to decline whatever can be declined. Thus, the surname Kołodko should be declined, and indeed, it often is: I often heard "ministrowi Kołodce". Yet, some people, including politicians, insist - against the language norm - that their name shoud remain undeclinable. That was, for example, the case of the former PiS minister Zbigniew Ziobro, a case widely known in the Polish media world. He wanted TV and press journalist to leave his surname undeclined, yet the linguist who was telling the story to us at a language training at work, said the former minister was not right demanding this. Some surnames, however, may be left undeclined by tradition, but I am not able to give you any examples right now.
As for the name Kościuszko, I think the fixed historic tradition is to decline the surname, so you should always hear: Naród zaufał Tadeuszowi Kościuszce.