Although I assume a philologist to be sensible about words, this could simply be an issue of word games because Prof. Erler isn't a native speaker of English. I remember that the tenor in the German literature on eudaimonia tends to interpret the term as "living/having achieved the good life", which is close to your definition, Don.
But then you're back at square one in needing to define what the "good life" is. Trying to satisfy the tranlated meaning of a word as polysemous* as eudaimonia in any one single word in a target language is going to present problems.
I would agree that there may be some word games going on, but "flourishing" seems to be the academic consensus of what word to use for eudaimonia. I've seen it used by other professors and academics, including those in involved with positive psychology research and promotion of that discipline (which I agree has some benefits and useful research to impart). I've just never got the same connotation from that word "flourishing" when it comes to applying it to eudaimonia.
*I can't stop using "polysemous" since, think, Pacatus used it in a recent post. It's a great word that conveys translation issues in one tidy word.