Hey I will drop my feedback below:
Onboarding
At first I thought that I had to drag the cards to the timeline. Idk if the timeline concept will be familiar to non game dev players.
I didn't get what the number in the top left corner of the card is.
The amount of mechanics felt a little overwhelming.
UI/UX, Is the text clear?
Not a native speaker here either but I think it works fine.
Ease to read (not a native speaker here)?
I think sword icons should be flipped horizontally to make the icon more easy to read at a glance. The enemy is on the right and most languages reading order is left to right, because of that it makes more sense that they point to the right instead imo.
Besides I think backwards and forward movement would be better represented with left and right arrows respectively since the movement is horizontal in the game.
The turn icon reads more like a circle with an marker atm, I would suggest adding hour marks or a better silhouette so it feels more like a clock.
Stun level and stamina icons use very similar colors and the shape is not too different either, it makes it hard to differentiate imo.
Is there too much going on?
Yeah, I think so. Maybe you could introduce mechanics more gradually.
I feel like visuals hierarchy could be improved too to make all the things a little more understandable, increasing timeline size and the icon size for the cards effects could be a start. The layout feels off too, the stamina is too far away from the cards (stamina sinks).
Attack previews are to faint to be clearly noticed and the highlight animation is a little annoying with how much the color changes and how small its space is.
I think you should work with basic UX/UI principles in mind first to make it work. E.g. reading order (up to down with a left to right scanning, like book reading), making squint tests for figuring out what is standing out more at any given moment and taking into account whats more imporant for the player at any stage of the game. Imo that's one of the hardest challenges in this information heavy kind of games.
Besides I think you should have some preset decks since it gets a little overwhelming having to create one while also testing a character or maybe the player wants to just play a match without having to create a deck.