Some silicones emit acetic acid fumes while curing... vinegar! When closed up in a speaker box or other, these fumes can get to wiring and corrode connections. More a problem with sealed boxes than vented.A better glue than silicone... E6000 or Alene's 7800. These are both "SBR Adhesives"... Styrene Butadyene Rubber. They are clear, much firmer than silicone, stronger, and still very slightly flexible. These glues are great for dissimilar materials, wood to metal, plastic to wood or metal, etc. It dries clear.
The solvent in the glue will attack some plastics, so test it first.
E6000 is the thickest, Alene's 7800 a little runnier, and a very thin version is sold as "Seal All". E6000 and Alene's 7800 are sold in the craft depart of Walmart, various craft and hobby stores. You may find the same material under other labels. Seal All is found in automotive departments, hardware stores, etc. This is too runny for our purpose here, mounting xover components.
It can be peeled up if need be, to change components for replacement or tweaking xovers. Best to cut through the glue with a sharp knife, then scrape off the remains with your fingernail.
With this glue I have NO fear of a heavy inductor breaking loose.
If you are going to attach the components to a brace I would advise a tywrap in addition.