Absolutely correct!
A very small track alignment error will translate to some level loss (i.e. when playing a tape recorded on another deck with correct track alignment, while if recording and playing on the same deck you won't see a level loss but you'd be simply recording an off-standard tape) but if the error gets larger then the backwards music from the other side would chime in (again, when playing a tape recorded on another deck with correct track alignment, otherwise while recording on the same deck you'd be simply partially erasing/overwriting the "overlapping" portion of R channel of the side you just recorded while you go and record the other side).
Anyways, if the heads have inbuilt guides (and the vast majority of them have inbuilt guides), if the guides are well aligned to the heads gaps/tracks the track alignment is OK, unless you aren't creasing the tape edges because the whole head (together with the inbuilt guide) is off... but if the guide wasn't put on the heads at the correct place (and sometimes it happens, believe me!) then the above problem will happen as described.
Each of the tracks on stereo cassette are 0.6 mm large (they are just thin!) , and the blank space between the L and R channels of the same side is 0.3 mm , so the whole width of the two tracks of the same side including the blank space between the L and R channels is 1.5 mm... which is , btw, the width of a mono track on cassette (so that there is some compatibility between mono and stereo).
The position of the tracks is substancially starting from the edge of the tape surface, with Left channel as the external one at the edge of the tape.
The same goes at the other side of the tape for Side B, of course.
All the rest, at the center zone of the tape surface, is the blank space between the two sides.
WOW... this time it would have been much easier (both for myself and for those who read it) to directly find a drawing showing the tracks, than describing them with words!
But, you know, I am not that fond of the easy ways of describing things... why making it easier when you can make it more difficult?