Write to hello@144mahjong.com. One person reads that address and answers most messages within a few days.
The messages worth sending, in order of how quickly they get acted on: a board that has stopped loading or throws an error; an advert that covers the game instead of sitting beside it; a factual mistake on a page — a wrong studio, a wrong year, a rule described incorrectly. All three get fixed rather than filed.
Requests for a specific title are welcome and are answered honestly. Some games cannot be published here because their publisher does not allow embedding, and when that is the answer you will get it plainly rather than a promise.
If you develop mahjong games and want yours listed, the submission page explains what to send.