I would like to make the diagram
\documentclass{article}
\usepackage{amsmath,amsfonts}
\usepackage{tikz-cd}
\begin{document}
\[
\begin{tikzcd}
A \arrow[r, bend left=40, "H\circ r", ""{name=U}]\arrow[r, bend right=40, "K", swap, ""{name=D}] &\textbf{Abcd}\arrow[Rightarrow, "\eta", from=U, to=D].
\end{tikzcd}
\]
\end{document}
perfectly symmetric. I've been trying to change the parameters after the bend left/right option but I don't think this is the right way to proceed. Is there a standard way to act, which is "robust" with respect to the whole diagram?
