Nonsense - of course I can make this statement -
Televue do not use and have never used Lanthanum in their eyepieces.
It is obvious from a marketing perspective that if they "did" use Lanthanum they would be boldly stating this point everywhere in their advertising.
This is why they go to great lengths to promote that their refractors as made in the USA and downplay that their eyepieces are mostly (a few still come from Japan) made in Taiwan.
A lack of transparency by Televue in their manufacturing/production processes isn't a positive feature - quite the opposite.
With respect to the optical properties and benefits of Lanthanum when suitably mated - I can't be bothered explaining this point. Suffice to say it costs more for a reason.