Well, there is long and detailed thread at the start of this page that begins with a comment from someone who started a different Democratic political software company and who turned down working on this app.
If you want a tl;dr, though, you might consider that (a) there's a paper trail, (b) the app was always intended to be optional and some precincts weren't using it in the first place, and especially (c) caucuses are not secret votes. That last one is how different campaigns had their own estimates before the official counts started coming out in haphazard fashion. Whatever bad things one can say about the idea of caucusing in general -- and we're hearing an awful lot of bad things -- they're actually pretty damn difficult to rig.
Buttigieg overperformed polling because polling only captures people's first choices. A lot of voters whose first choice candidates didn't meet the 15% qualifying point in the first round switched allegiance to him in the second, and the net effect was that a lot of moderates ended up in his camp rather than Biden's. This end result is probably an "only in a caucus" thing, but it doesn't require nefarious intent.
If you're to sabotage the caucuses and you're writing the software that tracks it, there's a thousand far more effective ways to do so and many of them wouldn't immediately shine a spotlight on you directly.
For malfeasance to remain undiscovered you need to be smart and clever.
For the kind of malfeasance that concatenates an SQL query with user input and then shows the whole thing to the user in an error message, you don't need that.
