Interesting - but I wonder what the purpose is, considering that all four gospels have dozens of translations and the Four Gospels are Divinely revealed Truth? Do we need a custom version that's cut and pasted such that it's on the whims of one's own perception of reality and bias?
And although I love the Douay-Rheims translation, it certainly tries to add Catholic content where there is none (translating "repent" as "do penance" for example).
That's St. Jerome's doing actually, and the DRB simply followed his lead. He translates the Greek "metanoeo" with the Latin phrase "paenitentiam agite". There is a spiritual reason, and it goes back to the OT -- Jerome was maintaining a spiritual continuity in his translation.
To do penance is to repent, otherwise it's simply an exercise in varying degrees of masochistic behavior and thought. The point of penance-as-act is not to torture a person, but to assist them in the transformative process of metanoia. Why else would Fr. say "For your penance, say 3 Hail Mary's and 2 Our Father's"? To torture us with prayer? No, don't be absurd. But to have us think of our former sin and our current hope in the context of a transformative, real, personal, and continuing relationship with God.
That these two words and concepts have become divorced in the minds of Catholics, Orthodox, or whomever has such a misunderstanding, is not a fault of the translation, but a loss of understanding its larger meaning.
The most sure penance is to engage in charity. To make up those holes in our past by filling the present and future with what we lacked or forsook in order to sin. If I say a harsh word to my wife, I repent and then do penance by kind language. If I leave the scene of an accident in a parking lot "hey... uh, it's only a scratch" and then confess that later, my penance is indeed some prayers. But, moreover, there is likely to come a day where I have someone convict me by leaving a note with all their contact info -- something I did not do in my own sin -- and I have an opportunity to forgive them and absolve them of anything owed to me. THAT is penance because it is necessitated by repentance as you are understanding it. One begets the other, but not the other way around.
Repentance is the seed of the fruit, penance. Penance without repentance is just stupid, and not the teaching of the Church despite your flawed understanding therein.