fasmg mostly compiled sorces line by line or one complete syntax construction by another one.
So for fasmg core is unmatter would be another lines for compilation or it is a last one line (if that line finish syntax construction).
Of cource forward referenced constructions is another deal.
But if we suppose that part of code will be untouched by forward references of rest of code - could we store compilation process at that point. And later we could assign another following text but we not launch compilation process from zero we restoring compilation with already prepared syntax constructions.
This solution could affect compilation time - we could start with prepared instructions set, file format, and other stuff.