Also, simply compressing the vocals to begin with can help a lot to bring them out front, which seems like what you are after.
(multiband compressor even better so you have more control)

Once the vocals stand out more, less frequency tinkering on other tracks is needed.
That coupled with panning the other sounds around the centered vocal may reduce the need for what you are trying to do.
Just a thought


Make your sound your own!
.. I do not work here, but the benefits are still awesome