(There are more open questions in the dictionary. Ones that are specifically about an existing word go in the word's Notes field; to search for them, put "Open question" in the Notes box.)

The adjective/noun distinction

I've written a lot about this in this comment and its subtree. In this below comment, I started to change my mind.

Directness

I need to deal with concepts of directness. In English, we often say things like "directly cause" drawing a relevant distinction between that and indirect causation. The distinctions are very important. I should probably have a different verb for that. I already spent zo, so maybe zyu?

There might also be a need for "directly say" or perhaps "indirectly say" while tel means directly say. Maybe tʌl.

Quantifier problems

I've discussed this one in the comments on quantifiers. I have no idea what a good approach is.

Talking about difficulty and cost

Original thoughts (when I saw it as "practically can" vs "technically can") in this comment.

I need to distinguish, though, between difficulty meaning a probability of failure, and cost. Sometimes we say something would be 'hard' to do, even if we could definitely succeed, meaning it would be costly. And there are also cases where it seems like both are applicable: "Gwyn is a hard boss" could be seen as meaning that if I try, I'll most likely fail, but it's also clear I could eventually win by trying enough times, so it kind of also means it just has a high time cost.

Emphasizing different sides of degree modifiers

There are pairs like "almost" versus "not quite"; or "slightly" versus "barely". Note that in either case they designate the same degree but one emphasizes the positive side and the other emphasizes the negative side. Currently Spem doesn't do separate words for this. Arguably, nur should be understood as "slightly" and "barely" should be conveyed with neni nur. But I feel it's a problem that I can't currently convey the meaning of English "partially" in the positive sense, because nor specifically means a medium degree, whereas partially covers anything that isn't complete; and nu kir emphasizes the negative side.

This is very similar to the question of whether "but" should exist - it means the same thing as "and" (that both statements are true), but implies a notion that the two are in contrast. I hate the word on principle because that "contrast" is such a vague idea and there are so many ways to use it to create harmful ambiguities. But maybe it's too useful to not have. I don't know. I haven't thought much about "flow control" words like that, but I'm attracted to the idea of having different sentence-linking conjunctions to specify what the relationship between the sentences is supposed to be (for example, one that means the preceding is a sort of preface to the following). I just don't like this one. But maybe any kind of word like that would have this problem, and I'd see it with the others if I used them for a while.

I have the adverbs jo and mo to indicate consent and thereby talk about rights. But there's an ambiguity: if I steal and you whack me in the head to get your stuff back, there might be a sense where it makes sense you did this without my consent, but it doesn't carry the moral weight it normally does because I don't need to consent to giving back stolen property. Maybe we need both pairs of words.