According to linguist & Tolkien scholar Ryszard Derdziński, sources on the family's history (& the surname's historical use) indicate the "tollkühn" etymology is unlikely. He instead argues the etymology is "from Low Prussian (Old Low German) nickname Tolkin 'son or descendant of Tolk'... where tolk means 'interpreter, negotiator' (< Old Prussian [Baltic] *tulk- < Proto-Slavic *tъlkъ 'sense, translation, interpretation, explanation')."Source: "On J. R. R. Tolkien's Roots in Gdansk" (published 2017, translated from Polish by Juliusz Żebrowski) pp. 10-11. [noted -ed]
Source: "On J. R. R. Tolkien's Roots in Gdansk" (published 2017, translated from Polish by Juliusz Żebrowski) pp. 10-11. [noted -ed]