I had a house once with cork flooring. Previous owner had applied some sort of clear varnish. The mottled pattern of the cork hid any indentations or damage caused by small stones or standing on lego. I suspect a solid colour would show up damage more?

I recently had a problem covering up marks on a plaster wall. Three coats of emulsion had no effect on the marks at all so I resorted to a coat Ronseal Damp Seal and then a final coat of emulsion to get the colour right. The Ronseal covered the marks well but I don't know if it is compatible with the Osmo.

I'm thinking of putting cork tiles on my freezing kitchen floor and had a look at a couple of 'solid colour' pre-varnished sample tiles. All of them still have the cork structure visible and look pretty 'cloudy' (in colour). So I guess this is a general problem. You can get cork tiles with fancy printed/laminated designs on top, which I guess are hard-wearing and not 'cloudy'. Maybe put another layer of those on top?