can't load world with Aether mod

FORGE 1.12.2

So I installed the Orbis designer gamemode mod, which worked perfectly fine, then I closed the game and installed the aether mod, which was installed successfully, but then when i created a new world, Minecraft suddenly quit and displayed the following message:

The game crashed whilst exception in server tick loop
Error: java.lang.ClassCastException: com.gildedgames.orbis_api.world.WorldObjectManager cannot be cast to com.gildedgames.orbis.lib.world.WorldObjectManager

could it be the 2 mods interfering?

btw what does coremods mean?(see crash report) And how does it affect me?

crash report:

---- Minecraft Crash Report ----

WARNING: coremods are present:
  PhosphorFMLLoadingPlugin (phosphor-1.12.2-0.2.6+build50.jar)
Contact their authors BEFORE contacting forge

// My bad.

Time: 11/15/19 2:07 PM
Description: Exception in server tick loop

java.lang.ClassCastException: com.gildedgames.orbis_api.world.WorldObjectManager cannot be cast to com.gildedgames.orbis.lib.world.WorldObjectManager
	at com.gildedgames.orbis.lib.world.WorldObjectManager.get(WorldObjectManager.java:80)
	at com.gildedgames.orbis.lib.world.WorldObjectManagerEvents.onWorldTick(WorldObjectManagerEvents.java:18)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_169_WorldObjectManagerEvents_onWorldTick_WorldTickEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.fml.common.FMLCommonHandler.onPostWorldTick(FMLCommonHandler.java:274)
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:776)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668)
	at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:185)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
	Minecraft Version: 1.12.2
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 365722264 bytes (348 MB) / 939524096 bytes (896 MB) up to 2147483648 bytes (2048 MB)
	JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	IntCache: cache: 0, tcache: 0, allocated: 20, tallocated: 86
	FML: MCP 9.42 Powered by Forge 14.23.5.2768 9 mods loaded, 9 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

	| State     | ID                | Version       | Source                                        | Signature                                |
	|:--------- |:----------------- |:------------- |:--------------------------------------------- |:---------------------------------------- |
	| UCHIJAAAA | minecraft         | 1.12.2        | minecraft.jar                                 | None                                     |
	| UCHIJAAAA | mcp               | 9.42          | minecraft.jar                                 | None                                     |
	| UCHIJAAAA | FML               | 8.0.99.99     | forge-1.12.2-14.23.5.2768.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHIJAAAA | forge             | 14.23.5.2768  | forge-1.12.2-14.23.5.2768.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHIJAAAA | orbis-lib         | 0.2.0         | orbis-lib-1.12.2-0.2.0+build127.jar           | db341c083b1b8ce9160a769b569ef6737b3f4cdf |
	| UCHIJAAAA | aether            | 0.2.6         | aether_ii-1.12.2-0.2.6+build127-universal.jar | db341c083b1b8ce9160a769b569ef6737b3f4cdf |
	| UCHIJAAAA | orbis_api         | 1.12.2-1.1.12 | orbis_api-1.12.2-1.1.12a.jar                  | db341c083b1b8ce9160a769b569ef6737b3f4cdf |
	| UCHIJAAAA | orbis             | 1.12.2-1.0.14 | orbis-1.12.2-1.0.14.jar                       | db341c083b1b8ce9160a769b569ef6737b3f4cdf |
	| UCHIJAAAA | phosphor-lighting | 1.12.2-0.2.6  | phosphor-1.12.2-0.2.6+build50.jar             | f0387d288626cc2d937daa504e74af570c52a2f1 |

	Loaded coremods (and transformers): 
PhosphorFMLLoadingPlugin (phosphor-1.12.2-0.2.6+build50.jar)
  
	GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
	Profiler Position: N/A (disabled)
	Player Count: 0 / 8; []
	Type: Integrated Server (map_client.txt)
	Is Modded: Definitely; Client brand changed to 'fml,forge'