While trialling your plug-in I encountered a problem.
The error message was:

W: awesome: event_handle_key:567: error running function: ~/.config/awesome/cyclefocus/init.lua:49: attempt to index global 'cyclefocus' (a nil value)

I followed the instructions in the readme, to summarize my config:

local cyclefocus = require("cyclefocus")
clientkeys = awful.util.table.join(
    awful.key({ "Mod4" }, "Tab",
        function (c)
            cyclefocus.cycle(1, { modifier = "Super_L" })
        end)
)

This is causes by a definition problem, the cyclefocus variable is referred to at definition time. This causes the variable to be always nil.