From the Elixir documentation for left |> right

The second limitation is that Elixir always pipes to a function call. Therefore, to pipe into an anonymous function, you need to invoke it:

some_fun = &Regex.replace(~r/l/, &1, "L")
"Hello" |> some_fun.()

Alternatively, you can use then/2 for the same effect:

some_fun = &Regex.replace(~r/l/, &1, "L")
"Hello" |> then(some_fun)

Your first example would looks like

"Hello" |> String.reverse |> String.upcase |> (&("Weird text #{&1}")).()

You module should work with that changes:

defmodule Test do
	def fx(x) do
		"Weird Text #{x}"
	end

	def try(str) do
		str
		|> String.upcase()
		|> String.reverse()
		|> fx()
	end
end