Thank you mr Alex and "Animal" for sharing, yes, I think I will switch to renderer but have another quick question... if I just do not tie a column to it, can I still do a custom filter? have not tried just yet, as I have been very busy. thank you for all your effort in resolving this.
Support Forum
As a workaround, we recommend to omit/change real field name and use custom renderer only for the column where you don't use custom filter function to avoid potential problems with filter sync. Your solution will also work well in case a column with custom filterField and filterFn will be placed before the second column that uses the same field name. But now it is not possible to have 2 columns with same field name and using different custom filterFn for both.
Btw, we are already working on this problem, when bug will get "resolved" status it will be possible to download nightly build on the next day after that and have the fix. We will update docs to describe how it works, so please review it as well to have a full picture.
All the best,
Alex