The author of Corail's Tombstone appears to have a beef with the author of Gottschcore, Gottsch, because Gottsch decompiled code from Corail's Tombstone, which is an All Rights Reserved mod, but ... Gottsch apologized and removed any and all of the code belonging to Corail's Tombstone from his mod, but this was apparently not enough for Corail, which resulted in Corail 'blacklisting' any and all of Gottsch's mods from being used alongside of his tombstone mod.
As for Tfarcenim, Corail developed a beef with him because Tfarcenim added a patch to his mods to prevent Corail's Tombstone from crashing the game if Gottsch's mods were present.
A truly indefensible position in my opinion, Corail chose to take a measure that ultimately hurts the users of the mod, by causing his mod to act in a covert and malicious manner, and that is likely against the guidelines that mod authors have to follow in order to have their mods hosted on CurseForge.
For any mod authors seeing this, this code was kindly contributed by asie over at the modded Minecraft sub-reddit, and was released under a Creative Commons Zero (CC0) license (as seen in the original post here) it should be able to be implemented into a mod to prevent Corail's Tombstone from crashing the game in the aforementioned manner.
The v4.0.0 version of Corail's Tombstone for Minecraft v1.12.2 presents malicious behavior by causing the game to refuse to load on start-up if any of tfarcenim's mods are detected as part of your modlist, it throws a custom exception claiming that tfarcenim's mods violate the 'license' of Corail Tombstone.
[--:--:--] [Client thread/ERROR] [FML]: A custom exception was thrown by a mod, the game will display an error screen and halt.
ovh.corail.tombstone.proxy.ClientProxy$1: Corail Tombstone Exception
at ovh.corail.tombstone.proxy.ClientProxy.lambda$new$5(ClientProxy.java:170) ~[ClientProxy.class:?]
at ovh.corail.tombstone.proxy.ClientProxy.init(ClientProxy.java:60) ~[ClientProxy.class:?]
at ovh.corail.tombstone.ModTombstone.init(ModTombstone.java:70) ~[ModTombstone.class:?]
Caused by: java.lang.RuntimeException: you loaded a mod not respecting the Tombstone's License making it incompatible : Tfarcenim's Mods
... 51 more
This also apparently happens with other mods, such as Gottschcore, and appears to be done on-purpose and with intent by the mod author as seen in this GitHub issue, be warned: