Regarding the 12A certificate, you'd think that the marketing team would have learnt lessons from Thirteen of saying a ride being so scary when in truth it never was in the first place but alas like thr Japanese military in the Godzilla films who always keep trying to shoot at him yet never make a dent in him, nothing was learnt from the marketing team then.
Though TBF, Sub Terra if I remember being on it back in 2013 did in some ways seem justified due to the ride's content, my only criticism of the ride was the ending being rushed when they could have had guests remained trapped in the dark pit with the feeling of Nemesis monsters crawling around you before they send you back up in which they lock the floor below you (much like the alien in ExtraTERRORestrial at WDW) and you walk, not running, over to the exit lifts in which in perhaps a post show sequence could be some Phalanx representative saying apart from a few hiccups (ha!) Everything went fine and that they hope to see you again (translation, re-ride) before the lift doors open and you're back up on the surface again.
A more slowed down climax could have helped make the experience better in which in conclusion the first two halves of the ride experience was good but ultimately they dropped the ball on the final part. No idea what we'll have in store here but I'm curious to see what it might be.