Hey, thanks for playing and commenting on it! Yeah, that's how you get to Jr. The bombs will actually walk most of the way, all the way across the bridge, as long as you don't stomp on them. In a previous version, I had two gaps where the fireballs were, but I thought I'd save the requirement to carry a bomb for the optional path, and this also made the path to Jr. a little easier.I played this course and ended up on the Bowser path. Overall really solid level. Nice telegraph on how you expect the bombs to be used.
I'm assuming to reach Bowser Jr you needed to destroy that third brick barrier with bombs, the one up and back a little bit? I was small so by the time I noticed it I wasn't taking too many risks. I tried running a bomb there but about 3/4th the way I got nervous and tossed it. If you want to make it easier maybe add a bomb pipe ahead so that one could back track to it if they want to? Maybe it's easy to reach as is, though. I didn't try hard.
Overall I liked it and gave it a star!