My understanding is that vim.cmd.xxx is somehow equivalent the vim.cmd('xxx').

There are no specific specific support for vim.cmd.call.

What you try to achieve is probably best using:

vim.fn["Vote"]({'name':'Phil Collins', 'band':'Genesis'})

My understanding is that vim.cmd.xxx is somehow equivalent the vim.cmd('xxx').

There are no specific specific support for vim.cmd.call.

What you try to achieve is probably best done using (vim.fn):

vim.fn["Vote"]({name='Phil Collins', band='Genesis'})