Should I expect problem to run Metalua generated byte code on a Lua 5.2 VM?
You would have a problem - 5.1 bytecode is not compatible with 5.2.
Your best bet is any tool that transforms original source into valid Lua source, and then compile that. Unless some clever person has a 5.2 -> 5.1 bytecode transformer[1]....or you can persuade Fabien that it's important to do the ML port.
[1] would be mostly mechanical - that word 'mostly' is the problem ;)