Acts 1:18 and 1:19 are typically translated as background information by the narrator on Judas who is mentioned via direct speech in Acts 1:16 and Acts 1:17. This is sometimes expressed through parentheses around the content of verses 18 and 19.

The English translation of Acts by C. H. Rieu (publ. 1957) uses a footnote for those verses, which is uncommon, if not unique, in Bible translation, but adds a sense of authenticity.

It says:

This refers to Judas’ death through falling headlong on a farm he had bought with the wages of his sin; his stomach burst open and his bowels gushed out. All Jerusalem heard about this, and the place acquired the name, ‘The Field of Blood’, or, in their language, ‘Akeldama’.