I managed to correct the 'tab' problem by replacing corresponding the spaces in the 'default.conf' file with '\t' and enabling the 'show tab character' option. When the 'show tab' option is disabled, CB saves the 'default.conf' file with replacing the the 'tabs' of abbreviations with spaces, is that intended, shouldn't it still keep the tabs in the '.conf' file? Anyway there is still the problem with 'share config' not copying 'auto complete' settings.
I'm also having this 'parentheses mismatch' issue which is annoying me for a long time. Whenever I enter one of the characters '( [ {' CB automatically inserts the corresponding closing version but with a mismatch color and the 'caret' blinking in red. Blinking and mismatch reset only when the caret passes right to the closing character. I deleted the 'default.conf' to solve this issue but didn't work. That's the reason why everything in this topic started.

Any ideas?