Syntax and morphology are largely solved problems at the frontier of NLP. If you think that this is not the case, then I must ask by what metric do you make that judgement? We have machines that are able to transcribe human speech and infer intent with lower error rates than humans for the same task. QED.

Formal semantics was hard at the time that loglans were codified. It was hard until very recently in fact. But that is no longer the case: Davidsonian event semantics is now expressive enough to give exact, unambiguous semantics for every desired utterance. There are still many unsolved problems in the field of semantics, but they are problems of the sort "what's the best way to represent..." not "how do we reconcile the two main theories giving totally opposite results."

For an overview of the modern state of formal semantics I suggest this work, which successfully dissolved the last lingering major conflicts in the field:

https://link.springer.com/article/10.1007%2Fs10988-014-9162-...

Isn't there a language spoken in Africa with a similar concept? I remember vaguely that there was a minor scandal some years ago because a politician said something like "Unfortunately, we couldn't finish the project in time" and the translator used the wrong form, so it sounded like they never intended to do so.

The latter is commonly encompassed by the subjunctive mood in Romance languages, although that also covers other meanings, depending on the specific language.