I have some more comments/ideas for improvement.
1. For plurals, I recommend adding reduplication (lak x2 = laklak). It's possible it's already there and I just never saw it.
2. For prefixes and suffixes I recommend adding vowel harmony as a possibility. (lak -> lakwa, fig -> figwe) I saw one instance of something similar with consonants (shiks in plural was zhikz), and that was interesting.
3. The words for 'black' and 'white' (and the negative) are boring because they always fit the pattern "rV". I would recommend removing that constraint and letting them be more random.
4. Negation seems to always work the same way. I would recommend making it more like plurals with a variety of forms. (e.g. lak 'frond', zamu 'plural', o 'negator' -> lakozamu, olakzamu, zamuolak, zamulako, lakolak, olaklak, etc. etc.)
5. The word order for 'antidote' (neg-death death-poison-water) is always the same. Why not mix it up for each language? Similarly the word order in the titles of certain other texts.
6. The wording "Shovel! Dig!" on that text confused me a bit. Maybe something more ambitious like 'Dig herbs and potatoes with shovel!' - more fun to work out :)
Hope these are interesting and/or helpful!