Without ClamSentinal, which is a separate program which integrates with ClamWin AV but requires a separate download and install, ClamWin AV has no resident components that can interfere with Avast.
Something in ClamWin AV updater has changed that causes Avast to sometimes alert when ClamWin’s signatures are updated. However, even with the alert, it hasn’t caused a problem with either Avast nor ClamWin AV.