We've played a bit more on another computer. It still feels a bit sluggish to respond, but that could certainly be from being an unoptimized Linux build. It was playable on that system and only had a slight feel of lag, compared to the initial tests which were too slow to really be playable. Thinking on it more, I'm betting that the issue with my initial tests was it being on a 4K screen, and wouldn't let me reduce it down much, even when not in full screen. With the system only having a 1660 GPU it likely wasn't up to the 4K resolution.
After being able to actually do a bit of fighting at a decent speed, our overall opinion is still that it has potential, but needs refining. We only played with the complete character. There is a nice variety of moves overall, a good selection of directional attacks and counters, and we like that some can have multiple followup options. The moves list and practice mode were helpful. We were surprised that the time limit is for all rounds. We had not been paying attention to that, and assumed it reset per round, so had a round 3 fight end pretty quickly after starting due to time running out. Once you know that is how it works you can plan around it, and it will be less of an issue for those who are familiar with the game and their character's moves, but as we were still learning we messed up moves and had other slow downs to gameplay. The lag is something that should get sorted with more optimized builds, and adding some video settings to adjust resolution and quality to match the GPU it's being played on. Since the only modern fighting game we play is Soul Caliber and that is not in your mentioned list of the games you are basing this on, we are not the best at judging how well those aspects work for the kind of gamer who knows and likes those systems. It feels like a good start for a fighting game.