Stay on Top layer or go to Power Plane
[I'm posting this as an answer, because I'd like to post a picture.  This is more of an extended comment than answer.]


  We are not on high frequencies


The trace in question is a part of the power path circuit.  It's not switching.  But if we look at the parts of the layout that are switching, they are badly laid out.  Switch mode converters can be layout-sensitive.
[It's somewhat hard to discuss this, because components aren't designated on the layout.]


  What is best ?


A good (possibly best) approach is to try to make your layout close to that of the bq24165 evaluation module created by TI.


(source: p.12 and ff here.)