Leaflet how to convert a L.CRS.SIMPLE coordinate to a normal L.CRS.Earth one

Question

I have a leaflet map set with a CRS of L.CRS.SIMPLE and several Markers. The tiles are custom tiles pulled from my server (the usual /zoom/x/y.png) format.

I'm building a mobile app with Android using the same tiles and so using Google Map the coordinate system is different but I would like to reuse all my Markers coordinate.

Is there a way to convert the marker's simple coordinate to a coordinate that can be used on the google map coordinate system ?

More info: The map is a fictional game map that I have tiled myself from a hung PNG file. I had set my Leaflet MAP CRS like this:

crs: L.Util.extend({}, L.CRS, {
                code: "simple",
                projection: L.Projection.LonLat,
                transformation: new L.Transformation(1, 0, -1, 0)
            }),

The WebApp let users add their own Markers on it, I had saved all the Marker lat/lng using what the leaflet map was giving.

I'm now trying to build a native Android app using the exact same tiles which works fine however I do not know how to put all the Marker on it since Google Map use the normal earth lat/lng coords.

Is it even possible to covert from L.CRS.SIMPLE to whatever Google Map uses ?