Schneider-Kreuznach Optics is the maker of B+W filters.
Here is a link to their Home Page in English:
https://www.schneideroptics.com/I could not find any reference to this sterilizer on the Schneider-Kreuznach page.
UV-C works by breaking the nucleic acids in a cell, thus upsetting the DNA chain. (UV causes a reaction between thymine molecules.) You can read all about it in Wikipedia, of course. <smile>
https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiationhttps://en.wikipedia.org/wiki/Direct_DNA_damageWhether UV-C can penetrate the typical lens glass is unlikely. But there is ample material on line about glass transmission properties, so that could be investigated. Of course, lens coatings are another matter. Coatings are often anti-reflective or UV-blocking and so may also block this gadget's UV-C output.
Sterilization with UV works only via line-of-sight, so any fungus lurking in interior threads or not reached by UV would not be killed.
As Owner-Admin of UltravioletPhotography.com, I feel I must provide a warning about UV-C, which is extremely dangerous to human eyes and skin. If UV-C can break up bacterial or fungal DNA, then it can also break up human DNA. And UV in concentrated UV-Led form can cause UV burns to your eyes.
Finally, I note that even if any fungus was killed within a lens using UV irradiation, the spores and filaments would remain. You would still have to open the lens and clean out the fungus.