As forge 1.13.2 is here you should update mod for 1.13.2
https://files.minecraftforge.net/maven/net/minecraftforge/forge/index_1.13.2.html

We're blocked waiting for Mixin. See this forum post for more info.

Also, should update makes it sound like we're in some way obligated to update which we are not, just to make that clear.

@crazybytes
Pretty sure there are mods which add invisible light sources. I'd suggest asking in some general modding place (e.g. ftb subreddit), someone will probably be able to name you one such mod.
If there are no other torches or glowstone in your structure, then I think you could even use a resource pack to change one of their models to be invisible.
Also, if you just want everything illuminated, you can press Z in the replay viewer, though that might look bad if there are places which should be dark.