To answer your first question: While yes, you can run Truffle languages without the Graal compiler, performance is going to be abysmal, as Truffle heavily relies on dedicated optimizations provided by Graal.

Consequently, you can also run TRegex as a regular Java library without Graal, but performance is probably going to be worse than java.util.Regex if you do that.

If there is any demand for it, I can put together a drop-in replacement for java.util.regex containing TRegex as a standalone maven library, but to really get any benefit out of it, I'd highly recommend using it in conjunction with Graal.