If I understand what you’re trying to do correctly, you will need to create a plugin to make that modification (or fork the entire discourse repo and use that in your app.yml, but that is absolutely not recommended).
I know, “plugin” sounds like overkill because it’s a big word. But all a plugin really does it modifies/amends discourse’s code, which is exactly what you’re trying to do, right? Of course you can do so much more with plugins than change 2 lines of code, but changing those two lines is entirely possible and not overkill at all. It’s pretty much the same as what you’ve tried, only the “proper” way. It’s so easy that even I was able to do it:
Check out that topic and see if you can make it work for your case.
Let me speak from personal experience about why modifying source code is a bad idea. Before working for Discourse I worked for a company that used Discourse internally. They had linked it to a WordPress install, and instead of using the API to connect WP to Discourse they decided to add a custom route to Discourse. They did this by copying the routes.rb file, adding the new route, and then overwriting the routes.rb file any time Discourse updated. As new routes were added by Discourse they were “removed” by the modified routes.rb file that was overwriting it. Eventually the homepage route was modified and we overwrote it on update, causing Discourse to frequently throw errors.
The file was modified in mid-2016. We started seeing errors in mid-2017. It took nearly a week to track down the cause of the errors, because we assumed something had changed recently, not something that hadn’t been touched in a year.
tl;dr: Don’t modify files directly. Even if they don’t hurt you today they can come back and bite when you least expect it.
I am not a coder either. Did you read the topics linked in the previous posts?
There is always room for improvement, but I don’t think that’s a fair assessment. You are trying to customize discourse beyond what is foreseen in the UI (which is very easy to use). If you want to “hack” a software, you can’t really blame it for that being difficult.
Besides, the community here is usually quite helpful…