That’s not what rom rebuild does at all - it moves data past 16mb into areas past 16 mb where there are a bunch of 00s (eg. space you wasted while always writing to end of rom with febuilder) - and it should be used only as a last resort when you hit 32 mb, as it is prone to creating bugs.
What? They’re talking about creating a romhack in febuilder.
There might be existing projects with this goal; consider having a look around at what has been done first. If you’re new to this, you should check out these resources:
