I wonder about the ethical and legal implications of this work. We've all read and watched sci-fi that warn about the implications of doing this, but biologists agree that reducing diversity within a population makes it much more at risk.
Liquid Types are more limited than "full dependent types" like Lean, Rocq, Agda or Idris. In Liquid Types you can refine your base types (Int, Bool), but you cannot refine all types. For instance, you cannot refine the function (a:Int | a > 0) -> {x:Int | x > a}. Functions are types, but are not refinable.
These restrictions make it possible to send the sub typing check to an SMT solver, and get the result in a reasonable amount of time.
I think the (hidden) reasoning is that it is really easy to have speedups with slow interpreters. However, getting speedups in high-performance level programs is quite hard, mainly due to micro-optimisations.
That's where the comparison to Python comes from: getting speedup on slow interpreters is not very _relevant_. Now if your interpreter has the same optimisations as Python (or v8 or JVM), even a small fraction of what you show would be impressive.
Having said this, the work your team did is a really challenging engineering feat (and with lot more potential). But I do not believe the current speedups will hold if the interpreter/compilers have the level of optimisation that exist in other languages. And while you do not claim it, people expect that.