I don't think it is fair to say pu is not accurate, It merely disagrees with how a lot of the community had come to use the language at that time. You could say it was inaccurate if it was supposed to be a report on common usage, but it is as explained; just how Sonja uses the language. Since it is technically the official book from the creator of the language, say version 1.0 of toki pona, it is probably more accurate at this point to say that if the community disagrees with its usage, then they are being inaccurate. Of course she has kindly allowed derivatives of toki pona as long as they follow certain rules. However, I think it is fair to say that there are a few proto-dialects of toki pona. The differences are so slight that for the most part, you would be hard pressed to even recognise where the differences are.
This issue about what words mean and how to use them, I see this as a big issue in toki pona.
Commonly people learn the words, by reading the words in the definition, and then forming a kinda of semantic blob to encapsulate that word. With this semantic blob in place they use the words in various contexts and POS that together are closest to meaning what they intend to say. Now they don't do this with all words, just most of them, some words have meanings which they realise are quite distant semantically, so they kind of form a couple of blobs for them instead. I think all words work like this, although Sonja doesnt explicitly specify this is how the dictionary is intended to portray words, it seems quite clear from the way the dictionary is formatted. All words tend to have a hierarchy of meaning; that is they are divided into senses; and semantic points, within those senses.
Here are some examples of how this plays out, and why this makes a big difference:
1. Someone blames me for something, I respond, "taso, mi suwi"
-> most people are going to think this is like me acting all cute, as if to say, im too cute to do that. This is because they have blobbed the meaning of the word, and lost alot of expressibility with it. It actually clearly means in that context; "but, I'm innocent"
2. New people arrive we do not know, I say, "mi mute li wile pona e ona"
-> most people are going to think this is like me acting all assertive, as if to say, lets fix them. This is again because they have blobbed the meaning of the word, and lost alot of expressibility with it. It actually clearly means in that context; "lets befriend them".
3. Someone asks me to read a document to them, I say, "mi ken ala kalama e ona"
-> most people are going to just be confused, because they have blobbed the meaning of the word, and lost expressibility with it. It actually clearly means; "I can't recite that"
I have come across this thing a lot, people that have been using the language for a fair while, and have little idea what the words mean. Trying to "teach" me, that say, pona is just all kinds of "good", whatever you think that is... this is wrong, pona is a much more objectively defined version of "good", ie - friendly, useful..etc.... They have singular and small semantic blob scope for each word, and often fail to understand how to use said words in different POS! Their expressibility is severly crippled and they use the lang for games of how to express simple things, very crudely.
Of course this won't solve the problem of topi pona to english exactness, but I think it might at least help a little.
Follower of the official dialect of toki pona as presented in the official book; Toki Pona, The Language of Good by Sonja Lang.