Forgot to update it here: The circuit is charging the coin cell but the led indicator does not work. I am not sure if it's because I got a cheap chip from Aliexpress or what else ... The circuit is almost the exact copy of the reference implementation from the data sheet. The  charging LED is on all the time and does not turn off. However the chip is charging correctly. Once the cell is full the amperage going to the cell is almost zero.

thanks for the quick reply! I'll see what my chinese clones will do :)

the ICs (probably also china-clones)  I did get do work fine (with normal lipo- batteries). And also the charge LED is going off if ready

the datasheet said LOW when charging and HIGH when done, hmm... 

When you use an led between VDD and STAT, the led is on when charging. 

Aahh, I thought your chip was putting it out differently from what you expected... makes sense now.

so, does it work? because I've copied your design (checked back with the datasheet as well) for a LIR2032 and was wondering about any updates.

There is nothing in this circuit that shouldn't work. It is basic circuit from MCP73831 datasheet, as per manufacturers recommendation; I used it in a few projects before, some of them are here on HaD.io

That was actually me trying to bring someone to update his project ;) I started with the datasheet as well but got the idea here. Later I compared the resistor values with his and took the formula from above to get values for a standard 2032 version.