There are two simple ways to put all of the serial punctuation in parallel without requiring even a split-second's pause by the reader to figure out what goes with what.
Option 1. Use semicolons after the first three serial entries:
I am involved in all aspects of these projects: attending client meetings; selecting material; compiling information; and, most importantly, redesigning entire wings of the schools every time stakeholders change their minds.
This is the option presented by jakePhilly, with one alteration not relevant to punctuation: I changed "material selection" to "selecting material," to bring that entry into syntactical parallel with the other three entries (which begin severally with attending, compiling, and redesigning).
Option 2. Use parentheses for the "most importantly" comment:
I am involved in all aspects of these projects: attending client meetings, selecting material, compiling information, and (most importantly) redesigning entire wings of the schools every time stakeholders change their minds.
In this instance, you can revert to commas at the ends of the first three entries, without any fear of punctuation overlap with commas that are performing other tasks.
For some readers—including Kris, to judge from the comment attached to jakePhilly's answer— mixing serial and parenthetical commas doesn't hinder reading speed in the slightest; for others (such as me), the slowdown is real though very brief; and for still others, the multiple commas may bring reading to a full stop, at least temporarily.
Punctuation is there to help readers recognize with less effort what elements are supposed to go with what other elements in a sentence. If you are satisfied that the way you've punctuated the sentence fulfills that purpose, then you should proceed to the next one with a clear conscience—and without any concern that out there somewhere exists a single right way to have punctuated the sentence, than which none so great can be conceived.