@BlueHazzard
After further investigating it myself, it seems that IDE is parsing compiler output using wrong settings. It seems it pulls regex, that parse the output, from what is set in the current Project compiler, while instead it should use Target comnpiler settings. Compiler settings for error parsing I'm talking about are here, in C::B IDE: Menu - Settings - Compiler... - then the "Other settings" tab - then "Advanced options..." button.
So, if it happens that the project has the same compiler set in both those places it works as expected, because it ends up using correct regex anyway. If it indeed functions how I see it so far.
I did used global compiler settings in the IDE, added or removed my own compilers there, so I may have made some mistakes that cause additional errors. As you mentioned, these are important. However I've tested on different C::B versions and problem seems to persist.