There was a discussion here a few months ago regarding the exact 30mm system being fitted to the CSC, it would seem that the MARLIN-WS 30mm is being replaced by a new turret and gun combination.
Leonardo has unveiled its new X-Gun 30x173 mm weapon system, accounting initial customers in the naval domain, alongside the three-barrel Gatling 20 mm and under-development single-barrel Blaze 30x113 mm weapon in a media tour at its Brescia facility.
www.navalnews.com
From what I can gather, Lionfish is the new line of remote weapon systems designed by Leonardo to improve on the Marlin mount. The X-gun is a Bushmaster competitor which can take NATO standard 30mm ammunition while having the same rate of fire, but apparently more selectable options for alternative fire rates and better suited to the role of countering unmanned systems. Better ammunition, more ready rounds alongside increased reliability and easier maintenance tied up in an enclosed stealth mount. Positive upgrade in capability if the marketing is to be believed, Leonardo has a pretty good track record for systems like this.