As long as the other moms were nice about it and promised to talk to their boys, and as long as you were nice to them as well, then it doesn't really matter what your impressions were as to whether or not they thought you were over-reacting. The boys came on your property after what is a typical curfew during the week, but this was a Saturday night, and they rang your bell, ran away, and crank called you. As long as they keep it to that one time then I'd really let it go and not dwell on it.
You might also think about your description of your reaction to a childhood prank that was truly harmless. You were "livid." You were "angry." Pranks like this are meant to be silly and frustrating... so I think by the description of your day, the kids were wound up, you were wound up and exhausted and probably already on edge, and this little incident pushed you right over.
::snipped::
The so-called pranks that upset me most are ones that include property damage, theft, and harm to animals.
EDIT: With your "what happened" and clarifications, as well as noting that you've had problems with these boys before, I amend my answer a bit. I have a lot more empathy for you now. :-)
In my original response to you I was under the impression that this was a first-time offense with these boys. Since you've had problems with them before, it's a pattern of harassment even if they're not causing property damage and harassment is also illegal. So from here on out call the police. Especially since if they continue to do it from here on out, it either means their parents didn't talk to them as promised OR the boys didn't take their parents' warnings seriously.