Russ, I'll look at this a piece at a time. Everyone, bear in mind I'm giving my opinions - it's not word of law or anything like it. (And no, I'm not picking on you - we actually agree on a few points.)
bfplayingcards - Your indices can move a bit closer toward the cut border. You want as many cards in your hand as possible.
Gee, that sounds familiar... Yeah, I mentioned that, and BF was already working on it - you can see some of the photos on the campaign page have indices closer to the corner.
Your pips in your pip cards can spread out a bit more on the card. A bit to much negative space.
To me, they're just fine. One of my favorite decks, Moth/Myth, had similar spacing - it looks so darn cute!
Your court cards need a suit indicator in your custom courts.
To me, that's optional, but I'll grant that if your art doesn't really fill the card's printable area, perhaps suit pips next to the court heads would look nicer. I'd have to see it that way to be certain.
The small pip in the indices doesn't cut it at a distance.
I would disagree. I held my computer at arm's length and looked at the mockups of the cards. I wear glasses but had no trouble. It would be different if the cards were on the far side of a poker table, but it would be no more different than any other standard index deck. If anything, size-wise they're a bit LARGER than normal - standard decks have a pip that's half the height of the value in the index, and these pips are nearly the same height. They're a bit narrow, perhaps, but it complements the art style and the design very nicely.
You could contact Kings Wild Project, Albino Dragon, Gamblers Warehouse, or Collectable Playing Cards and see they can sponsor you in the USA. I'm sure one of these guys wouldn't mind expanding their services. Another plus is they can also do fulfillment for the USA. Not saying Indiegogo isn't bad, but Kickstarter gives you a lot more exposer for success.
This is a good idea, though it would mean reducing the overall profits. It's an added expense to the project.
I have seen cases where an artist simply sells the design to another party, who goes on to produce the design and pays the artist a flat fee (a sizable one, if they're skilled artists/designers). You might or might not earn as much running your own KS project and you leave all the headaches involved with producing a deck in someone else's lap while you go and start the next project idea.
The fronts are beautiful and really deliver that art nouveau look and feel. But to me, the backs are completely disconnected from the organic and flowing style of art nouveau. True, they're intricate. But the look is all perfect circles and geometrics--almost the antithesis of art nouveau. For me, that's a showstopper.
P.S. Agree completely that the indices need to be closer to the edge--where they are now makes a bridge hand almost impossible to hold. I don't mind the plus-sized white space on the number cards--I love a pip layout that's a bit unusual, while staying legible. Like others, I do mind the lack of a large suit indicator on the court cards. You need to be able to tell at a glance what card is being played--and in many games the suit counts.
All of those are easily fixable ... but the backs ... oh man.
I wouldn't say the backs are hideous - but in the same breath I'd also have to admit that I've seen better and it doesn't connect as well with the art on the faces.
BF, I would recommend you check out
this booklet, affectionately known as "Mrs. Robinson's". This is the book describing the first 81 Bicycle back designs, and the table of contents gives the date in which the back was first issued. As the Bicycle brand has been around since 1885, you'll certainly find backs that are contemporary of the Art Nouveau era - perhaps something will resonate with you and give you ideas for a different design for your deck.
Most relevant for you might be the Cupid Back - number 21. The design has two interlocking wheels similar to your interlocking circles, but without the sudden termination of the circle "mid-lock". It could provide a little inspiration on how to modify your back design in a way that will really capture Art Nouveau. I'm no artist, but one thing I note of Art Nouveau decks is that there's some complexity and some simplicity in each design, giving it a feeling that's decorative but not overly intricate. You may have leaned a bit too far into the intricate side of things.
Also, as I look at a close-up of the back, two things stand out. First, the level of detail is so high, some of it might be lost when the deck goes to press, especially if you're doing the design in brown and dark yellow or brown and metallic gold - metallic gold ink is darker than most people realize. Second is that the circlular pattern is segmented and doesn't flow smoothly at all from one circle's quadrant to the next - there are visible lines separating them, and in some cases the edges meet in a very disjointed manner. The top and bottom have two "half-hearts" meeting along the center line, but one half is vertically flipped relative to the other, making for a shape that more resembles a capsule than a heart.