I wonder what sort of yields one can expect using limtek,
it's gonna be jimjam so full of jungle and n-oxide,
SWIM has not finish yet and weight + 4 grams from 200 grams potent bark.

There is some water in jimjam too (it's sticky) but still,

How can one know if his yields are correct using potent mimosa from a reliable source?

Depends if the product made by evaporating the solvent or salting out with vinegar/other acid

If it was made by salting out or dissolving in vinegar then that's a whole lot, congrats!

If it was made by evaporating it is nowhere near pure and will be nasty and inefficient to smoke. Personally SWIM wouldn't smoke it.
A simple process can make sure that you are only getting the actives and will be nearly 100% pure.
Dissolve whatever will dissolve in vinegar then let settle for an hour or two, decant off the vinegar then either evaporate it down to a concentrated tincture (SWIM's preferred method) or fully evaporate it until it no longer smells of vinegar (but not over 100C) and that will yield pure stickly freebase.

4g/200 is 2%, which is good but not unheard of. There is no way for someone on the internet to tell you how pure your product is, even with pictures (unless it's egregiously nasty). There are many purification teks available, and I'm sure one of our more learned members can suggest a good one if you want to preserve the jimjam, etc.

Q21, SWIM did the limtek salting out from d-limo with vinegar, then, he put this vinegar in the oven at 80°C to evaporate.
I quite don't get if you said this would be impure or not. Did you mean evaporating the d-limo instead of salting out with vinegar? If it i's this, SWIM salted out from d-limo with white vinegar.

So, would you recommend to redissolve this in vinegar, will vinegar sort of purify it?

If it is salted then it is very very pure.
Wow then, Nice yield. Enjoy it!