This language is over 20 years old, and nothing has been done about the utterly impractical numeric system of Toki Pona. I plan to propose a system WITHOUT changing the lexicon of Toki Pona in any way. (As always with toki pone, this is the choice of the speaker, but I wanted to propose it because multiple avenues have said the same thing)
As of right now, there are 6 numerical terms: ala(0), wan(1), tu(2), luka(5), muta(twenty) and ale(100) and those terms are formed in a romanic style to create other numbers(18 being luka luka luka tu wan, 5 + 5 + 5 + 2 + 1) which becomes insane the higher on the number line we go. (999 being "ale ale ale ale ale ale ale ale ale mute mute mute mute luka luka tu tu") So instead of being purely addition based, I propose the system be a mixture of multiplication and addition.
I understand this may violate Toki Pona's minimilist nature and the whole purpose of Toki Pona, hence why it hasn't been revised before, but think about it: which is more important? The utilization of a numerical system, or the minimalism of a language? I cannot say the same for you, but I'd rather be able to use any tool given to me.