The word ‘sockdolager’ appears neither in Benson, nor in Wells, nor in Vikivortaro, nor in Vikipedio, nor in ReVo, nor in Sonja. So, how should it be rendered in Esperanto?
What about one of these
- definitiva solvo
- definitiva respondo
Cf. Merriam Webster’s definition of sockdolager in English.
The linked example phrase in your question could then be rendered like this:
Esperanto is the sockdolager of the language barrier.
Esperanto estas la definitiva solvo de la lingva problemo.
You need to focus more on expressing ideas and not translating words. You've posted several questions of this form -- citing obscure English words and giving no clarification (other than nested links) of what idea you're trying to express.