Another excellent resource for European languages. Their Polish section frequently hosts high-quality translations for classic cinema.
Because the film is in the public domain in many regions, you can find various subtitle files across major community databases. If you are looking for (subtitles) to pair with your copy of the film, these are the most reliable sources:
H.G. Wells’ 1936 sci-fi masterpiece, Things to Come , remains a landmark of cinema, depicting a century of war and eventual utopia. For Polish-speaking fans of classic science fiction, experiencing this vision of the future is made easier through dedicated translation efforts. Where to Find Polish Subtitles (Napisy PL)
This is the most comprehensive database. Look for entries titled "Rzeczy, które nadejdą" or simply the English title. You will often find multiple versions synced for different file formats (BRRip, BluRay, or DVD).