STM32 products are nothing but problems ... ;(
Magic happens. Today I launched SW4STM32 opened that project that did not work yesterday and...no problems at all, no "could not be resolved" errors, not even single warning. Everything builds nicely o.0
Maybe as @dautrevaux said, sometimes indexer is behing and therefor project exporer can't find right files so in turn complains about unknown references. Ehh anyway, that's why people tends not to like Eclipse...
Thanks you all for contribution in this subject and help 😉