I purchased the cousins strap for my non ceramic sub. Same problem as you, the spring bars did not fit. I used a small drill bit and reamed the strap holes out with it by hand. The spring bars then fitted the strap but it was such a tight fit to my watch that I still couldn’t use the original spring bars. I ended up buying smaller bars to make it fit.
Had the Everest previously and had to return it as it just would not fit my watch no matter how hard I tried. Can’t compare them quality wise as I never got to use the Everest but the cousins one is decent for the price.