With the new tanks system, NMEA2000 tank systems have no way to name tanks. My TankRepeater (no longer usable as of v2.70~15 ) provided a /CustomName property and as I understand it, the analog tank inputs also have a way to customize the name.
I don't know where the service names are coming from but "Black water (sewage) tank (1)" is wayyyyyy over the top in terms of a label for the tank tiles in the Mobile Overview. Even "Fresh water tank (2)" is more than will fit on the tile.