Privet bonsai yellow leaves after severely cut

[Strator]

The seller said it is an indoor tree. Not long ago when problems started with it i found out that it is a losing fight and i have to keep it out. I can do it (balcony to the south), but I am afraid that it will hurt even more because all autumn and winter tree was at home and now in Poland I have about 5 degrees Celsius at night. Earlier, I had no problems except drying the tree (2 branches withered to be cut) because I watered too rarely. The leaves began to turn yellow about a month after repotting and severely pruning the tree. I thought it was a stress after pruning because the leaves only turn yellow where I cut. Branches where I haven't cut are intact. I spot black and white spots on leaves. Some leaves are damaged but the cat could do it. I watered the tree and sprinkled the leaves with a fungicide. On the photos you dont see yellow leaves because when I spot one I immediately cut it. Leaves on the branches are small amount after drying. New ones have not grown in their place, so I make ramification and cut new shoots to stimulate the side shoots and dense branches with leaves.
What can I do next?

 

[Shibui]

Tree looks OK.
Evergreen leaves only last a year or 2 then turn yellow and die while new leaves have grown to take over. If yellow leaves are all inside low down that's normal.
Low light can also cause yellow leaves. No point having leaves if there's not enough light so some go yellow and drop off.
Pruning should not cause yellow leaves but it may make older, yellow leaves more visible?
I see wire on the branch. Is that wiring recent before yellow leaves? Sometimes bending can cause break in the branch, even if you cannot see a break. That can interfere with sap flow and cause dead shoots and yellow leaves.

I agree that outdoors would be better. Privet can cope with temps below freezing.