The answer is because of the sources of the two translations.
The DR is a translation of the Latin Vulgate which as the word “paenitentia” rendering the Greek “metanoete”. Of course, translating “paenitentia” into English naturally comes across as “penance”. Because of the DR’s source, “penance” is the only acceptable option.
But most modern Bible versions translate directly from the Greek, in which “metanoeo”, which, literally, means a “change of nous”, where a “nous” is one’s orientation or attitude towards something. “nous” is something like “mind” when used in the phrase “change my mind”, i.e. one’s attitude towards something, concept or object. So a “metanoia” is a complete change of orientation, attitude.
If the original “nous” was something wrong, e.g. sinful, then to “meta-nous” literally means to turn away from the wrong “nous”, in other words, to repent. Because of its strong reference to one’s interior disposition (i.e. “nous”), the word carries with it a call to full conversion. For translations made directly from the Greek, “repent” is the most suitable verb.
Regardless, any translation, be it Latin or English will never carry the full force of the original.