The Forge Version of the mod [Forge 1.16.2/3/4/5] v6.0.0.194-alpha isn't compatible with 1.16.4 as the name says.
1.16.4 provides Language Provider v35.1
1.16.5 comes with v36.1

I assume that also counts for lower versions (1.16.2/3) as it requires at least v36

net.minecraftforge.fml.ModLoadingException: Mod File RoughlyEnoughItems-6.0.0.194-alpha-forge.jar needs language provider javafml:36 or above to load
§7We have found 35.1
at net.minecraftforge.fml.ModLoadingException.lambda$fromEarlyException$0(ModLoadingException.java:64) ~[?:?]
at net.minecraftforge.fml.ModLoadingException$$Lambda$2889/1241182310.apply(Unknown Source) ~[?:?]
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[?:1.8.0_51]
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502) ~[?:1.8.0_51]
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) ~[?:1.8.0_51]
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_51]
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418) ~[?:1.8.0_51]
at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:270) ~[?:1.8.0_51]
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502) ~[?:1.8.0_51]
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[?:1.8.0_51]
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_51]
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[?:1.8.0_51]
at net.minecraftforge.fml.ModLoader.(ModLoader.java:114) ~[?:?]
at net.minecraftforge.fml.ModLoader.get(ModLoader.java:148) [?:?]
at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$1(ClientModLoader.java:103) [?:?]
at net.minecraftforge.fml.client.ClientModLoader$$Lambda$2886/1450830187.run(Unknown Source) [?:?]
at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$4(ClientModLoader.java:123) [?:?]
at net.minecraftforge.fml.client.ClientModLoader$$Lambda$2887/65894433.run(Unknown Source) [?:?]
at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:103) [?:?]
at net.minecraft.client.Minecraft.(Minecraft.java:437) [?:?]
at net.minecraft.client.main.Main.main(Main.java:149) [?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_51]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51]
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51]
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.4-35.1.37.jar:35.1]
at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$411/1564078808.call(Unknown Source) [forge-1.16.4-35.1.37.jar:35.1]
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?]
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?]
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?]
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?]
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?]