I have proved $latex (\mathsf{RLD})_{\mathrm{in}} \Omega^{\mathsf{FCD}} = \Omega^{\mathsf{RLD}}$ (where $latex \Omega^{\mathsf{FCD}}$ is a cofinite funcoid and $latex \Omega^{\mathsf{RLD}}$ is a cofinite reloid that is reloid defined by a cofinite filter).

The proof is currently available in this draft.

Note that in the previous draft there was a wrong formula for $latex (\mathsf{RLD})_{\mathrm{in}} \Omega^{\mathsf{FCD}}$.