A suggestion: I'd recommend using Tree Notation (https://github.com/breck7/treeprogram) for your storage format, instead of JSON. (disclaimer: author of TN)
I can actually help you build your own language on top of TN using some new tools, if interested, which might be very useful to you. Email is in profile.
First, it would support current functionality, so you wouldn't lose anything. So everything that it adds is a net gain.
Second and biggest benefit, I believe it would allow them to add features more easily because they'd easily be able to build a simple and well structured Nulis DSL in Tree Notation that removes a lot of the incidental complexity of their current code.
Third, it would make their "nls" files human readable and writeable. No more quotes or brackets, et cetera. With a few tweaks to their current implementation, folks could then drop in more file structures that can then be visualized and edited in nls.
A suggestion: I'd recommend using Tree Notation (https://github.com/breck7/treeprogram) for your storage format, instead of JSON. (disclaimer: author of TN)
I can actually help you build your own language on top of TN using some new tools, if interested, which might be very useful to you. Email is in profile.