I didn't run into any playability issues on a 1920x1200 monitor, and I thought this was a really clever puzzley game!
The only issue that I ran into was that I would sometimes try to make movements too quickly for the game, and end up not having any frog selected after clicking on the frog I just moved. It felt like there was some sort of cooldown timer after moving where you couldn't reselect the same frog again, but it didn't feel intuitively communicated (especially because the UI was still showing the frog's range as I hovered over it).
That was the only point of friction I ran into though, and I really loved the tension of trying to sneak an extra frog into a tight space, then realizing that you've created a cascading problem pushing them all apart. Once it clicked that I could use that cascade to my advantage (to consolidate smaller gaps together), I got really into the frog stacking.
Sadly, I only maxed out at 84 croakiness, but I had a very good time doing it :)