There is a company called Intrum, which was called Intrum Justitia from its founding in 1923 to a merger in 2017. This strikes me as a clear attempt at making a name sound more prestigious by making it feel like Latin. The name does not seem to make sense, although it is easy to imagine that something like "inside justice" was intended. Perhaps Intra Justitiam would have felt less grandiose.
Was intrum ever a real Latin word? Or are there perhaps other relevant words that might shed light on this one? I have never seen the word, but that doesn't quite rule out the possibility of a rare or post-classical word, especially pertaining to legal language. There are similar words like inter and intra and intro, and taking a leap and imagining a first and second declension adjective behind them might lead one to intrum.
There is always the chance that Intrum is the name of something that the company was named after and the resemblance to Latin is a coincidence, but I found nothing pointing in that direction.
(Just to be clear, I am in no way affiliated with the company. Nor do I think I could, given the quality of their titular Latin.)