Oh yeah, sorry, forgot to answer!
The launcher looks good, I recreated it and tested it, it largely did the job:
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It depends on how you computed your staging sequence though, in particular for the second stage. In this case, after the first stage separation, I only ignited the 2 side stages and left the central core turned off. Then once the side stages were empty I separated them and turned on the central core.
Apart from that it's a good launcher, the only change I would make is that I would assemble the first row of boosters with the central stage, to make a single first stage. Your rocket lacks a little of punch after the boosters are dropped, this will fix the problem and make your staging sequence simpler.
If you still fail the problem might be your flight technique, there should be a way to optimize your trajectory. That should work however.