AFAIK there is no functional tag to tag this entrances at airports, so data consumers cannot translate into the language of their users, so for now, the only option is to use a translated descriptive name. The fact that polish word is on the board at promintent font size, and english word are also probably on the board, maybe with a smaller font as secondary name, due to the widespread use of english, does not means that in OSM other languages shouldn't be tagged.