Is this a special concept in Greek? I cannot make any special sense of a 'joyful wish', although it is of course syntactically correct.
It seems to me that in this context ευχή refers not to a wish that you are making for yourself, but a wish (blessing, well-wishing) for someone else, be it on festive or on other occasions. The Greeks have a lot of these wishes/greetings, and you will hear them often (here is a nice list). So what is actually meant would be such a wish made on a joyful occasion, or at least a wish brought forth in a joyful way - expressing the joy and the positive feelings of the well-wisher.
Yes, this is a problem to translate. We have "happy/joyful" and would appreciate any other suggestions to give it more meaning. Oh, and it is something you will hear in Greek, around happy occasions.
I can't make much sense of it. I don't think I've heard it before. Χαρούμενη as opposed to what? Could it be μια λυπημένη ευχή; I don't think so. An adjective that goes well with ευχή is εγκάρδια.
Thanks for "εγκάρδια" (I think that's the one I've heard) we can only asdd it as an alternative right now but it can be added in the new tree.
If an answer is rejected it doesn't mean it's wrong necessarily it may just mean that we didn't think of it and add it to the translations. I'm adding "cheerful" now with many thanks for your contribution.