I cannot understant how the rollbacking  works. To rollback any changelog I should have both this changelog and a tag to rollback.
Assume next:

    -tag tag0 -migrate changelog1 -tag tag1 -migtare changelog2 -migtare changelog3
And now I wanna rollback to tag0. Is it possible? Or I always need "one changelog - one tag" policy?

It is usually best to have a single changelog containing all your changes.  You can break it up into multiple files, but them into a single master changelog.  That way you would call:

    -tag tag0 -migrate changelog -tag tag1 -migtare changelog -migtare changelog

and can rollback to either tag1 or tag0.