Example:
http://infinity-code.com/atlas/online-m … vider.html

Is it possible to add -y support for (custom) urls to support TMS?

More information can be found in the QGIS issue and I believe it was present in v2 of online maps.
https://issues.qgis.org/issues/15927

I've added it to the code myself and it seems to work

changed the regex replace from:
{\w+}

to:

{[-]?\w+}

And added the following lines of code in different scripts/variants:
if (v == "-y") return ((int)(1 << tile.zoom) - tile.y - 1).ToString();

Thanks!

Roy