For Proto-Søkkli I am in bad need of ideas for different kinds of derivation, as I have only a few such derivation paths, and find myself unnecessarily making noun-verb doublets where there really probably should have one derived from the other.
The current paths I have are agent noun from verb, gerund from verb with zero-derivation, adjectival verb from noun, and comparative, superlative, and elative from adjectival verb (which I do treat as derivation rather than inflection), diminuitive and augmentative of noun, and all different kinds of verbal and nominal compounding, and I am considering on adding result noun from verb. However, I do need more derivational paths than that.
In an early episode of Conlangery they discuss the "bignum words for snow in Inuit/Eskimo languages" myth. While this is glossed over, they do go on to mention that at least one language in the general region (I forget which) has a verb-producing affix that, applied to a noun, means "to be freezing in one's ~".
So when you're satisfied with all of the purely functional derivations, you may want to consider something uniquely culture-bound; perhaps something not otherwise easily expressed with a simple verb.
Some varieties of Quechua has a suffix that means "one who shares ~ experience with sb." So town-SUFF = compatriot/fellow citizen; person-SUFF = neighbor; work-SUFF = coworker, etc. Similar to 'mate' in English I guess except a little bit wider of a semantic meaning.
I tried adding some affixes for derivation of nouns from verbs, and ran into the problem that the nouns created looked distinctly different from other nouns, in that the vast majority of existing noun stems are a single syllable and the onset of a following syllable and a filler vowel to be added after that in some inflected forms, while derived forms are either bisyllables with a consonant cluster or long consonant after it and a filler vowel or trisyllables with a following consonant and a filler vowel. Yet the typical zero-derivation does not work because zero-derived "nouns" from verbs are gerunds or subordinate clause-like which take arguments (and may have subjects).
What ever happened with the quest for weird derivations? Did you ever consider weird subverbs or qualifier verbs? (I don't really see anything too out-of-the-ordinary in the Proto-Søkkli dictionary.) Relatedly, the last new dictionary entry for P-Søkkli and Sèćli were both about a month ago; do you have any more plans to continue developing the proto-language, or do you expect to focus only on the daughter languages now?