i know exactly what you mean - the real track plays fine but there are a couple of bars you don't like.

to expand on rharv's post, all you need to do is keep the original track, then generate a second track with the same real track and rb will play it differently. then you just cut and paste in/out the bits you don't like

or use another realtrack - play around see what you like - its so easy with RB but even though i've been using BIAB and PT for years its only with the upgrade to 2018 that i'e started with real tracks. it can be a steep learning curve (i'm learning every day) but its worth it.