No one seems to have made a list, though someone should have. The first thing to say is that most tpers can understand a variety of styles. The second is that they are not slow to "correct" what differs from their own preference. On the other hand, most of the things that get corrected now are the same things that got corrected in the early days. There haven't been many changes and the essentials remain-- and remain unfamiliar to beginners. But let's see.
1. There are half a dozen words that are not in the pu vocab or are listed as alternates which are considered fully functional. Check older lists for their meanings and uses.
2. 'pi' indicates a unit block within a string of modifiers, a break in the left grouping of each successive word. It is not a possessive marker. It cannot be followed by just one word (obviously).
3. 'kepeken' is a preposition, so, like all preposition, wherever it occurs, it's complement, the tool, follows immediately, without 'e'.
4. To speak a language X is 'toki kepeken toki X' or 'toki lon toki X'. To talk about X, is 'toki e ijo (pi) X'.
I'm sure there are more but these are the ones that turn up most. and they are not all that different from pu (a word that is not much used).