Actually all those loop types are supported in SNEX, if you take a look at the SNEX test suite, you'll see a bunch of test cases that use them:
https://github.com/christophhart/HISE/blob/develop/tools/snex_playground/test_files/loop/for_loop2.h
BTW, most features of the SNEX language are covered by a test file, so if you want to explore what is working, you can build the SNEX playground (tools/snex_playground), then click on the SNEX logo on the top left to load any test (there are about 500 tests in there). It's also a great way of reporting bugs within the SNEX language, so if you find anything, just write a test file that reproduces the issue and I'll add it to the list (that's how I implemented most of the SNEX language features).
However in most cases you don't need to write these manual loops and can just iterate every value of a container using the range based for loop. This is a known concept in C++ (and for(n in myArray) is the HiseScript equivalent.
https://www.cprogramming.com/c++11/c++11-ranged-for-loop.html