Why are there so many easily avoidable game changing translation errors in Dominion?
Sorry that this is not strictly an answer to the question, but it is too long to be a comment and it does give some information about where to find more.

From the late 1990s to the mid 2010s I was a frequent participant in the Spielbox discussion forum. During that time we had a couple of threads about that topic. This is a link to the oldest one from the archive (the site has since then moved to a new URL, but old threads are archived): Eurogames-Spiele nicht mehr kaufen.
Unfortunately the search engine will ignore "dominion" because of too many hits :-(
If you search for "Übersetzung" and restrict it to "Nur im ersten Beitrag der Themen", you will get 207 hits in the Archiv of Spieleforum. Several of them are specific to issues in one particular game, but often some people with insight (working for the publisher or translators) gave answers.

What I do remember from those discussions was different publishers have different approaches - some hire professional translators (sometimes translators with little or no ties to gaming, which is considered a big problem in the gaming comunity, because they lack the knowledge of particular or usual gaming terminology), sometimes games are translated by gamers with good English knowledge.  

On a few occasions some of the latter stated something like:


  I just got a pdf of the original language rules and had one(!) week to translate it. I didn't even get a copy of the game so that I could have played it at least once as I would have preferred. I know that the translation is not good, but it is the best that was possible under these circumstances


So if there is a short answer to your question, it is quite trivial: time pressure.