well , ELGG by Revo was one of the best in the past... but in 2019 june , we decrypted Revo 6.0 fully .
i dont advice to use it right now , there is better free compilers , example u can try encryption by hero gaming.
of course it can be decrypted too.
and about mainc topics.... yeah , i would tell that scripts can be encrypted saifly , there is some encryptions , which edits whole opcode . after editing script gets large size about 1MB+ and for human its almost impossible to reverse it's opcode , because of size .
such encryptions are not decrypted until today , all decryptors are avoiding themselfs to start working on decrypting such files... once again , reason is size and also opcode is differently edited in all cases by program , so its almost impossible to decrypt .
of course if program (at this way i mean Lua) can read, then it will be decrypted by human too , but as i already said its almost impossible and noone will waste his time for 1 script .