This question is open and being tracked within this GitHub Issue:
https://github.com/mengshukeji/Luckysheet/issues/260
i.e. item #5 = “how to add fontList and what is the format”
I began to look for you, here is what I followed in the source so far:
In core.js
https://github.com/mengshukeji/Luckysheet/blob/master/src/core.js
see lines 2 and 65 and 82
import defaultSetting from './config.js';
let extendsetting = common_extend(defaultSetting, setting);
Store.fontList = extendsetting.fontList;
also see
/controllers/menuButton.js
line 4486
defaultFont:["Times New Roman","Arial","Tahoma", …etc
https://github.com/mengshukeji/Luckysheet/blob/master/src/controllers/menuButton.js#L4486
also a few lines further down in that same file see this function:
fontInitial:function(fontList)