I based this on an "uncensored" NES ROM that I've had in my collection for at least the last 20 years, which I had always assumed was a fan edit/rom hack.
Well, there was absolutely* a prototype that originated within Lucasarts that someone purchased at some point, and I had the impression that at the time that the purchaser was resolutely against ever dumping it.
But that was a very long time ago, and I see TCRF has the dump available, so clearly something changed at some point when I wasn't paying attention. (What TCRF chooses to make available is their business, of course.)
*as much as anything on the Internet can be imagined to be absolute, anyway
SVM is actually able to read the PRG of the ROMs of the original releases, but not custom versions like this, due to the differences (like dialog or images) that require the right offset and length to be read properly. This is why I had to do it all by hand, which took me quite some time but it was a fun and rewarding pet project for me 
And your efforts are appreciated, to be sure.
I'm not sure what you were using exactly, but aside from using ScummVM directly, ScummVM has a specific
external tool for generating those LFL files. Would it be straightforward to make a patch for the source code of that tool with the relevant offsets and lengths..?
Unfortunately I expect the ScummVM team would not be interested in such a source code patch, but they have their own criteria for what they think is acceptable and I'm sure other people would still like to see it.

(I recall there was quite the nasty debate a while ago about combining the floppy and CD versions of some of the Space Quest games to make a superior version. The Steam versions of the Lucasarts games also deliberately shuffled some data around to make them incompatible with ScummVM – but it looks like ScummVM got official support for the Steam versions a while ago too. These things are weird.)