Having a nett gain of 3 power, in case of Glustyworp, or of 4 with Kayran, is not "backfiring", its a mediocre bronze play, thats it, but not a situation where you end up worse than you were, so no, as long as you have more than half a brain, Uma is not backfiring, ever.
Uma is going to be a thing since its a card that can singlehandedly win games that you´d otherwise loose because you dont have an appropiate answer for certain situations. Im sure my enemy was having a blast while he pulled Eyck of Denesle off his arse while i only had 1 card in hand which was not removal.
The speech of "its only going to be a thing in casual play" its the same speech i heard back when Create was implemented. Then, Tournaments were decided on DiscoveRNG.
Try it. Follow my advice. Put Uma in any of your decks, play with it for 20-30 games. Thats what i´m doing now, and the results are simply absurd.
I removed Kayran from the list because I forgot he had an order, my bad.
About Gullstyworp, if your 1 power unit is an engine card it backfires (in fact it can easily lose you the game depending on the situation).
Also, I'm sorry but I strongly disagree with you when you say that everyone is gonna play Uma because it's gonna provide the card you need.
1/ The way you put it, it feels like Uma allows you to just choose the card you want in the game, which is far from being the truth. I tried to play Uma (not in this version but that card didn't change, it's the same card, let's be clear about that) and I lost count on how many times it lost me a game single handed.
2/ Again, the provision system makes this card none competitive and you can quote me on that, I can even bet money and say that, it is and it will always be a bad card as long as they keep its effect and recrutment cost as it currently is. Think about how many cards you can pick for 11 PC, even if you're concerned about not being able to deal with something your opponent is playing there is plenty of control cards that cost less than that.
And even if you're very concerned Korathy heatwave cost 13 and basically reads "remove a problem from the board"...2 points for the consistency seems more than fair to me.
Also, as I said, this card existed before, it haven't been changed and it wasn't competitive in the previous Gwent, I don't see how it would magically become good especially when the recrutement system plays against it now.