I have updated the plugin Split Bar Rests to have an option to replace a bar rest with a normal rest as best as it can.
It will try to fill the bar using undotted or dotted rests, and if it cannot fill the bar with a single note it uses the largest possible rest it can and pads with other rests.
In some cases you may prefer to use one rest per beat or one of the other options. It should work fine for "normal" time signatures.