@McNigeria,

The dictionary has to be stored locally in order to keep lookup times fast. So all plugin edits are local and will only affect your browser.

That said, we anonymously save edits in a review queue where possible and there is a somewhat convoluted process for incorporating them in the main dictionary that involves their passing a manual review and getting tagged for things like part-of-speech, etc. So there is no guarantee that any particular edit will go into the dictionary over time, but it is not wasted effort for those hoping to help.