Hi,
Last time I looked at the source code, Lua didn't really have a concept of "ROMability", in the sense that you can't save data structures in ROM/flash and use them directly from there (without having to load then into RAM). In eLua it's possible to use the compiled bytecode directly from flash and there's also a "read-only string" type that keeps the *content* of the string in flash (just the content, not the whole TString data structure) and uses it from there. But all these require changes to the Lua source code.
Best,
Bogdan