I rebuilt the mod with the new Art Manager to "update" it to Atlantis as per recommended by developpers. I launched the game and my mod worked just as fine as it did.
I then proceeded to send it to two friends for them to try it, but it wouldn't work for them. Custom textures and UI pictures weren't loaded, the text tags from Modstrings does not load, etc. What I sent was the folder of my mod from "custommaps", only leaving .arc and .arz files.
Anyone else suffering the same issue? Have you tried to see if your mod runs on other machines?