Seems threadsafe enough

dependencies.gradle

@@ -10,4 +10,7 @@ dependencies {
 
     runtimeOnly("com.github.GTNewHorizons:Baubles:1.0.4:dev") // for Thaumcraft
     runtimeOnlyNonPublishable("com.github.GTNewHorizons:NotEnoughItems:2.5.4-GTNH:dev")
+
+    compileOnlyApi("com.github.GTNewHorizons:Angelica:1.0.0-alpha31:api")
+
 }

gradle.properties

@@ -33,7 +33,7 @@ channel = stable
 mappingsVersion = 12
 
 # Defines other MCP mappings for dependency deobfuscation.
-remoteMappings = https://raw.githubusercontent.com/MinecraftForge/FML/1.7.10/conf/
+remoteMappings = https\://raw.githubusercontent.com/MinecraftForge/FML/1.7.10/conf/
 
 # Select a default username for testing your mod. You can always override this per-run by running
 # `./gradlew runClient --username=AnotherPlayer`, or configuring this command in your IDE.
@@ -61,6 +61,9 @@ gradleTokenModId =
 # [DEPRECATED] Mod name replacement token.
 gradleTokenModName =
 
+# [DEPRECATED] Mod Group replacement token.
+gradleTokenGroupName =
+
 # [DEPRECATED]
 # Multiple source files can be defined here by providing a comma-separated list: Class1.java,Class2.java,Class3.java
 # public static final String VERSION = "GRADLETOKEN_VERSION";
@@ -123,7 +126,7 @@ includeWellKnownRepositories = true
 usesMavenPublishing = true
 
 # Maven repository to publish the mod to.
-# mavenPublishUrl = https://nexus.gtnewhorizons.com/repository/releases/
+# mavenPublishUrl = https\://nexus.gtnewhorizons.com/repository/releases/
 
 # Publishing to Modrinth requires you to set the MODRINTH_TOKEN environment variable to your current Modrinth API token.
 #
@@ -187,5 +190,3 @@ curseForgeRelations =
 # This is meant to be set in $HOME/.gradle/gradle.properties.
 # ideaCheckSpotlessOnBuild = true
 
-# Non-GTNH properties
-gradleTokenGroupName = 

settings.gradle

@@ -17,7 +17,7 @@ pluginManagement {
 }
 
 plugins {
-    id 'com.gtnewhorizons.gtnhsettingsconvention' version '1.0.8'
+    id 'com.gtnewhorizons.gtnhsettingsconvention' version '1.0.15'
 }
 
 

src/main/java/mods/railcraft/client/render/BlockRenderer.java

@@ -7,6 +7,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import net.minecraft.block.Block;
 import net.minecraft.client.renderer.RenderBlocks;
@@ -15,15 +16,18 @@
 import net.minecraftforge.client.IItemRenderer;
 import net.minecraftforge.client.IItemRenderer.ItemRenderType;
 
+import com.gtnewhorizons.angelica.api.ThreadSafeISBRH;
+
 import cpw.mods.fml.client.registry.ISimpleBlockRenderingHandler;
 
 /**
  *
  * @author CovertJaguar <http://www.railcraft.info>
  */
+@ThreadSafeISBRH(perThread = false)
 public class BlockRenderer implements ISimpleBlockRenderingHandler, IInvRenderer {
 
-    private final Map<Integer, IBlockRenderer> blockRenderers = new HashMap<Integer, IBlockRenderer>();
+    private final Map<Integer, IBlockRenderer> blockRenderers = new ConcurrentHashMap<>();
     private final Map<Integer, IInvRenderer> itemRenderers = new HashMap<Integer, IInvRenderer>();
     private ICombinedRenderer defaultRenderer = new DefaultRenderer();
     private final ItemRenderer itemRenderer;

src/main/java/mods/railcraft/client/render/RenderBlockMachineDelta.java

@@ -17,6 +17,8 @@
 import net.minecraftforge.client.IItemRenderer;
 import net.minecraftforge.common.util.ForgeDirection;
 
+import com.gtnewhorizons.angelica.api.ThreadSafeISBRH;
+
 import mods.railcraft.api.electricity.GridTools;
 import mods.railcraft.api.electricity.IElectricGrid;
 import mods.railcraft.api.electricity.IElectricGrid.ChargeHandler.ConnectType;
@@ -32,6 +34,7 @@
  *
  * @author CovertJaguar <http://www.railcraft.info>
  */
+@ThreadSafeISBRH(perThread = false)
 public class RenderBlockMachineDelta extends BlockRenderer {
 
     public RenderBlockMachineDelta() {
@@ -41,6 +44,7 @@ public RenderBlockMachineDelta() {
         addBlockRenderer(EnumMachineDelta.CAGE.ordinal(), new CageRenderer());
     }
 
+    @ThreadSafeISBRH(perThread = false)
     private class WireRenderer extends DefaultRenderer {
 
         private final RenderBlockFrame renderFrame;
@@ -240,6 +244,7 @@ public void renderItem(RenderBlocks renderblocks, ItemStack item, IItemRenderer.
         }
     }
 
+    @ThreadSafeISBRH(perThread = false)
     private class CageRenderer extends DefaultRenderer {
 
         @Override

src/main/java/mods/railcraft/client/render/RenderElevator.java

@@ -11,9 +11,12 @@
 import net.minecraft.util.IIcon;
 import net.minecraft.world.IBlockAccess;
 
+import com.gtnewhorizons.angelica.api.ThreadSafeISBRH;
+
 import cpw.mods.fml.client.registry.ISimpleBlockRenderingHandler;
 import mods.railcraft.common.blocks.RailcraftBlocks;
 
+@ThreadSafeISBRH(perThread = false)
 public class RenderElevator implements ISimpleBlockRenderingHandler {
 
     @Override

src/main/java/mods/railcraft/client/render/RenderTrack.java

@@ -14,13 +14,16 @@
 import net.minecraft.util.IIcon;
 import net.minecraft.world.IBlockAccess;
 
+import com.gtnewhorizons.angelica.api.ThreadSafeISBRH;
+
 import cpw.mods.fml.client.registry.ISimpleBlockRenderingHandler;
 import mods.railcraft.api.tracks.ITrackInstance;
 import mods.railcraft.api.tracks.ITrackSwitch;
 import mods.railcraft.common.blocks.RailcraftBlocks;
 import mods.railcraft.common.blocks.tracks.TileTrack;
 import mods.railcraft.common.blocks.tracks.TrackGated;
 
+@ThreadSafeISBRH(perThread = false)
 public class RenderTrack implements ISimpleBlockRenderingHandler {
 
     @Override