Hi, I am a fairly new bonsai owner and I am a bit concerned for my Carmona tree. For the past 2 weeks I noticed few mature leaves turning to a light green colour and even yellow. I was removing these 2-3 leaves every 2-3 days. 
Is this a watering problem? Am I watering the Carmona too often?
Also some leaves have tiny black spots, can these be due to a pest, spider maybe? I noticed this on some young leaves too.

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I don’t have other plants and the tree stays inside by the window.
The soil is a very compact type, it’s very hard to stick my finger in it to check the humidity but I am trying to water it once the surface turned slightly dry. I am also misting the tree leaves every morning. 
I have attached some photos with the tree and the removed leaves. 
P.S. it looks a bit naked because I just pruned it 3 weeks ago after I got it, to encourage new twigs and leaves to grow at the end of mature branches.

The black spots is their natural look, nothing to worry about. 

Carmona is a very fussy plant and the leaf drop you experience is a very common problem. It accelerates during winters when our heating kicks in. To be completely honest, I have not seen any long term healthy carmona grown in livingroom conditions. looking at their natural distribution, in humid subtropical climate makes me think they need cooler winters, more light and more humidity than we can provide. But it is still an unsolved mystery how to keep carmona alive long term in nortern temperate climates.

Thank you for your response, I was really worried about those black spots. Now I feel guilty for trimming some branches and leaves in winter. However I see a lot of babies coming out. 
I live in Romania, where winters are mild, my heating is coming from the floor and I keep a temperature of around 21C. 
I will try my best to keep its humidity high by spraying the leaves daily, but also be careful with the soil humidity. Will give an update in summer

Increasing humidity indoors in winter is very hard. A terrarium is the best chanse. In any case get yourself an humidity meter and measure what difference your actions makes.

And please come back to us and report any success or failure. We need all the information we can get to learn more about this tricky species.