I'm liking the variable aliases, like fps<-|->tick_lag, glide_size==pixel_step_size, etc., but they're only useful to me after I find out about them. Maybe the bounds variable is unstable or buggy or something, somehow. Or maybe you just forgot about it. I'm using it from now on, anyhow.
I would like, though, if vectors were supported natively. That is, like in Coggoid, properties that belong together should be the same variable.
For example, an equivalent of your x, y, and z would be pos = vec3(x, y, z). Colors would be vec4(r, g, b, a). Setting pos=1 would be the same as setting pos=vec3(1, 1, 1) since pos is defined as a vec3.
Vector calculations are definitely okay already (jt_vectors creates and garbage-collects new /vectors each operation), but a built-in alternative would be nice. Maybe I could make something using lists, but lists can't have chlidren.