Hi, Droni,
I don't have any expert advice to give on propagating these plants, but I can describe some limited experience at germinating seed or that of related species, if that is of any help?
I don't know anything about Lagotis brevituba but I found that seeds of Lagotis yunnanensis germinated rapidly (after 5 days) at room temperature (~20 deg Celsius) without any other treatment, and grew readily.
I found that Saussurea graminifolia, S. stella, S. nepalensis, and S. eopygmaea also germinated rapidly (in less than a week) at room temperature, while S. medusa took about 11 days under the same conditions. However, I only got one seedling of S. medusa which I was unable to keep alive long enough to plant out.
I had one seed of Gentiana urnula germinate after 11 days at room temperature, after a treatment with GA-3 (giberellic acid) but again, was unable to keep it alive.