I am a retired water scientist, not a medic, but I would avoid any device that purports to calcium and magnesium that occur naturally in chalk derived water as these are essential elements for things like bone structure.
A water softener removes calcium and replaces it with sodium, hence the salt regeneration requirement and an ion exchange resin.
Soft water is great for everything except drinking, and can be a health hazard.
The filter cartridge is the key part of all this.
It can filter solids (a sediment filter) and possibly some larger bacteria and microorganisms, but that's all.
An activated carbon filter is aimed at mainly organic compounds, some of which cause odour, but should not be in a public water supply.
Chlorine disinfects drinking water and if removed, renders the water non-sterile. Boiling or letting it stand is more effective for removing than a filter.
The answer by the BWT expert is curious in that by saying that their filter removes lindane ( a long banned organochlorine pesticide) and atrazine, suggests that the filter has an activated carbon element, then goes on to say that it removes lead (long since taken out of water supply pipework) which would suggest that it is also a resin based filter, so would remove calcium?
My advice would be to get a sediment and activated carbon filter, see the "furred" kettle as an indication of healthy water and avoid resin filters.
I would challenge the BWT expert to provide evidence that water company provided potable water has any level of lead in it that remotely comes close to requiring removal. You can request a lead analysis if you are concerned. Or for lindane as well.
Some of these claims are misleading and out of date