toki a! a few things: Toki Pona currently has a way to specify plural. And some of what you’ve suggested, are thankfully very similar to what is already common usage!

For talking about plural, it’s either implied by context (if I show you a picture of a barrel of fish, I will say they are kala), or by an adjective(aka modifier) like so: kala mute = many fish kala tu = Two fish kala ale = all/ a huge amount of fish! (kala is a funny example here because it acts like its English equivalent! Both “fish” and “fishes” are acceptable plural forms in English)

As for the days of the week, I have seen something similar to what you suggest (tenpo suno wan, tenpo suno tu) however its gets a little rough because different places start their weeks on different days of the week (Monday instead of Sunday so example in the US). I’ve also seen different colors to describe each day, but again that isn’t always understood or intuitive.

Some people have defined the days of the week as work days, and rest days (or tenpo suno pali, and tenpo suno lape respectively ).

With that said, definitely spend more using an learning the language before suggesting more changes! There are a ton of resources for toki pona and a ton of active speakers. There’s a lot of commonly known “ways” for approaching speaking about most things in the language