Hello, sorry for the late response. But thank you very much for listening to my feedback. I do have some responses to your points.
1. Yeah I can see designing a suitable visual indicator is no easy task, but maybe I can suggest also using a slashing smear effect but i a different visual?
2. Sadly I don't think I can come up of any reasonable way to fully prevent this outside of giving the players more iframes. Perhaps having some input buffer for player's action so that they can be executed immediately once the player is out of the stagger state helps? I do appriciate the effort on the team to experimenting a solution for this. But I can suggest at least address sections of the game where this problem is more prominent and causes more annoyance than it should to the player's experience. So far I can tell this issue comes from bosses that can spam heavy hitting attacks at a specific angle that is likely going to hit the player as soon as their iframes ends. From the demo these sections are the crab boss's 3 hit sword attack and the boss's 3 saw blade projectile attack. Perhaps tone down on the spam attacks in either their attack rate or attack damage. Or maybe make the crab attack end it's combo if it had landed a hit on the player.
3. About the damage number thing I did check my game and you were right about how the damage numbers are set and my game is not bugged. I guess I was too tired at the time to noticed it and I guess the fighting the boss constantly and dying to it in consecutive hits and had conditioned me to think every attack is lethal (which in my defense, 1.5 damage is still lethal). This point was the one where I was the least sure about anyway so I trust your judgement more on this one.
On yeah, one thing about the perfect run mode is that it's best to only show this mode on levels that the player have already beaten and indicate what is it fore (to help players attempt to get an s rank without needing to restart the level from the menu manually). We definately don't want new players mistaken that this mode is how the game should be played.
Anyways this is all I have. Again I am still very hype for this game and I will still get it once it is out so wishing you all the best in your efforts to complete this game.