Python and Lua are already well suited for the typical scripting tasks (plus there is good old Perl). And I would actually recommend them for any non-trivial scripts as the maintenance is so much easier.

I guess the selling point of Amber is the fact it compiles Bash so you can sneakily start using it without having to argue with your co-workers whether language X should be allowed in the code base. Plus, no worrying about having the right Python version installed. Though then again I am not sure the compiled bash is very idiomatic so probably still not easy to get into code review.