Converted CtB maps also sucks, not so much as mania however.
You can also search "mode=mania" or "mode=taiko", that removes all converted maps from the list.
Will there be an option to toggle this (with this being on by default)? Its a good idea anyways.
A good idea could be adding an option to enable/disable the warning, so players that do know the difference can play converted maps without being bothered by the warning.