I read these guidelines in the studio wiki:
en.doc.boardgamearena.com/BGA_Studio_Guidelines#II-6_Avoid_move_confirmations

and it seems to me that selecting a card doesn't qualify for a confirm action. It happens on every turn and really isn't that complex. So I'd ask for more information about why users might want this and how it should work. There are 2 ways this might be handled:

A. You click on a card and it highlights the card, then you click "confirm" above and the move is executed.
B. You click on the card and the move is executed, then above in the bar you are given 2 options: "Confirm", which would have an automatic 5 or 10-second countdown timer, and "Undo", which would take the move back if clicked in time. I would not do this without the timer, as this would definitely fall in the "bogs the game down" category of the guidelines document.

These options would potentially fix the following issues:
1. The card zones are too close together and you sometimes mis-click on an adjacent card. I'm guessing this isn't the issue, but would be fixed by both A and B.
2. You realize after the card arrives in your pile that you miscalculated how many you already had, maybe by not considering your hand cards. This would likely not be fixed by A, only B, but is also fixed by just getting better at the game. In all games here and in real life, we sometimes have remorse after a bad move.
3. rafiki_33 said they sometimes click the reflection card opposite the one they want. That seems odd to me. What is more intuitive than clicking the card you actually want? More elaboration please. This may also be solved by just gaining a little more experience with the game.

Another thought I have considered if it is issue #2, is that your hand cards could actually be shown in your score piles per player, but not showing to the other player or to spectators, but this definitely violates the guideline here:

en.doc.boardgamearena.com/BGA_Studio_Guidelines#III-2_Be_careful_about_player_assistance

So... this long post is justifying my decision so far to not include any kind of move confirmation. The game is short, and you might get another opportunity to still win even if you blunder a round. I believe if I had a move confirmation, after you became more comfortable with the game, you would probably want it gone later. But, I am not 100% set on this, so please clarify your issue and proposed solution choices, even if they are not listed here.

Thanks! And I appreciate all this wonderful feedback!

For now, I'm rejecting adding a confirmation option.