Hi, I think this usability bug deserves some attention.
You currently have to use z_sendmany to send from a t-address. That's confusing. Particularly when you use "getnewaddress" to get a t-address and "z_getnewaddress" to get a z-address. It follows that you should use "sendmany" to send from a t-address and "z_sendmany" to send from a z-address.
The first time anyone uses Z, they try using "sendmany" and get an obscure error message, meaning that people think they've lost their coins.