The difference between ice detected and severe icing is in the actions required - see #3, check the specific actions for the aircraft.
Getting to Grips with …
https://www.skybrary.aero/bookshelf/books/3404.pdf
The usual advice is that according to the aircraft type certification limitations, is that for ‘normal icing’ ** the flight can continue in the conditions, but remain observant.
For severe icing, aircraft type specific - e.g. rate of accumulation, location, effects, then the conditions should be exited, change of course and/or altitude.
Note that the met icing definitions do not relate to the inflight conditions experienced by aircraft, and that inflight icing PIREPS only relate to the reporting aircraft, but can be a useful guide.
I do not know about the airbus specifically, but would expect a detector to differentiate between rates of accumulation, clever physics. However, the crew must always check where the ice is forming, and remember that what can be seen on the wings may not be the same on the tail / fin which could have greater effects, (finesse ratio).
** No such thing as ‘normal’ ice; only good ice, bad ice, and hazardous ice.
Good ice is in the galley.