There's some truth to it, but it's mostly that junior developers and senior developers with no discipline that give it a bad name.

The major problem is that it has one of the the highest capacities for writting incredibly dense code there is, paired with very powerful language transformation tooling (i.e. switch statements were added as a module, but can also be used for funny evil.)

Yes! I actually had this exact desire years ago, and went searching for it. RegexBuddy does this, best $US 40 I’ve spent. It’ll even do its best to make something that’ll match the same things, even if you’re using features that aren’t technically supported in the target. Don’t worry, it’ll describe exactly what doesn’t work, and why, when it does that.

For example, if I ask it to convert from C# /(?>atomic) case-(?i)insensitive(?-i) string/ to JavaScript (chrome) it’ll throw out: /(?:atomic) case-[iI][nN][sS][eE][nN][sS][iI][tT][iI][vV][eE] string/, along with the warning:

Conversion is incorrect because the target application's regular expression flavor doesn't have certain features: JavaScript (Chrome) does not support atomic grouping