Python the language has been designed carefully to allow mixing floats and ints at runtime (some corner cases notwithstanding).
The issue appears to be about interfacing to other languages, where Python’s type system is too abstract. Maybe we should define new types that fit those languages better, e.g. int32 and int64, and float32/float64. IIUC numpy does something like this, and we could probably just use its names and conversion/coercion rules.