How can it be 'doing better' if it's doing worse?

I'm by no means an expert, and I don't grow Adenium, but your post gives me some ideas as to the performance of your plant:

1. Over-watering - first, it's winter right now, and you've increased soil volume. Wait for the soil to dry between waterings. Too much (or too little) water can cause yellowing leaves.

2. Nitrogen - again, too much or too little can cause yellowing leaves. You've added rabbit manure, which I'll assume is high in nitrogen...that could be the problem, especially since the plant isn't in its optimal growth-season conditions.

Was it blooming when you bought it? Did you re-pot while it was blooming?

The good news is that you have supplemental light....
but you should really allow the soil to dry out more between waterings, in my opinion.

Josh

in my case: if I water my adenium leafs will start getting yellow and fal off and also leafs get brown like burned one.

if I don't water Caudex gets soft and shrinking.
very difficult almost impossible in my case to "hit" the right line?

I know I don't have experience in Adeniums but what ever I try is wrong and/or opposite than what experts on this forum are suggesting.

Please, comment, tell me your story, give me advice I will listen and I will be thankful.

Thank you all

it was about to bloom when i got the plant and and i water when the soil is completely dry.

I did transplant when it was blooming

nitrogen levels could be to high or low i dont know maybe more research about rabbit pellets

In winter you should water adeniums very little.
I just spray the soil around mine once a week...don't actually water till spring.

lotsaplants it is blooming does that make a difference