If you can recall any specific hairy edges, please share! Without user feedback, the only use-cases I've had to guide improvements are the things I've done myself, like using Lilt to re-slice images for gamedev projects, writing test fixtures, doing bulk image-import, and the occasional code-golf puzzle.

That's a fun idea- thank you for sharing!

A few suggestions:

• Instead of using "," to join together long lists of string literals, you could use "split" on a single string. This is more concise, but also a bit more efficient at runtime, since Lil does not (currently) pre-evaluate constant expressions. The following lines are equivalent:

("A","B","CD","EFG","H","I")
"|" split "A|B|CD|EFG|H|I"

• If the random[] function is given a single list argument, it will select a single value from that list, whereas specifying a "1" as the second argument will produce a list of length one. The former case appears to be closer to what you want. The following lines are equivalent:

sum random[(1,2,2,3,4) 1]
first random[(1,2,2,3,4) 1]
random[(1,2,2,3,4)]
random[1,2,2,3,4]

• We don't strictly need to "fuse" in both syl[] and word[]; the string-cast of a list of strings is their concatenation, so a single fuse at the top level will collapse nested lists-of-lists-of-strings:

   (list "A","B"),(list "C","DEE","EFF") 
(("A","B"),("C","DEE","EFF"))
   "" fuse (list "A","B"),(list "C","DEE","EFF")
"ABCDEEEFF"

• We can simplify slightly by referencing cons/vow in syl[] as globals, instead of threading them through word[]/syl[] as arguments. Once syl[] doesn't take any arguments, we can observe that the "@" operator is a shorthand for the loop in word[]. The following lines are equivalent:

each x in i syl[] end
syl @ i

All together, I think I might factor this program as follows: