i dont know tudbut perhaps you can rewrite this

Client/src/main/java/de/com/baseband/client/Setup.java

@@ -49,6 +49,7 @@ public class Setup {
             new ChatCrypt(),
             new ChatExtras(),
             new ChatFilter(),
+            new ColourSign(),
             new Notifier(),
             new ClickGUI(),
             new Connect(),

Client/src/main/java/de/com/baseband/client/feature/modules/ingame/ColourSign.java

@@ -0,0 +1,51 @@
+package de.com.baseband.client.feature.modules.ingame;
+
+import de.com.baseband.client.event.events.PacketEvent;
+import de.com.baseband.client.feature.Feature;
+import de.com.baseband.client.mixin.mixins.ICPacketUpdateSign;
+import de.com.baseband.client.registry.annotation.Config;
+import net.minecraft.network.play.client.CPacketUpdateSign;
+
+public class ColourSign extends Feature {
+    @Override
+    public String toString() {
+        return "ColourSign";
+    }
+
+    @Config("Mode")
+    public Mode mode;
+
+    enum Mode {
+        Vanilla,
+        Spigot
+    }
+
+    @Override
+    public void onTick() {
+        meta = mode.name();
+    }
+
+    public void packetOut(PacketEvent event) {
+        if (event.getPacket() instanceof CPacketUpdateSign) {
+            ICPacketUpdateSign updateSignAccessor = ((ICPacketUpdateSign) event.getPacket());
+            String[] lines = updateSignAccessor.getLines();
+            for (int i = 0; i < 4; ++i) {
+                String line = lines[i];
+                if (line != null && !line.isEmpty()) {
+                    switch (mode) {
+                        case Vanilla: {
+                            lines[i] = line.replace("&", "§§0");
+                            break;
+                        }
+
+                        case Spigot: {
+                            lines[i] = line.replace("&", "§§§00");
+                            break;
+                        }
+                    }
+                }
+            }
+            updateSignAccessor.setLines(lines);
+        }
+    }
+}

Client/src/main/java/de/com/baseband/client/mixin/MixinProxy.java

@@ -8,10 +8,10 @@ import de.com.baseband.client.event.events.PacketEvent;
 import de.com.baseband.client.feature.Features;
 import de.com.baseband.client.feature.modules.chat.ChatExtras;
 import de.com.baseband.client.feature.modules.client.Client;
+import de.com.baseband.client.feature.modules.ingame.AutoSignText;
 import de.com.baseband.client.feature.modules.movement.Velocity;
 import de.com.baseband.client.feature.modules.render.NoRender;
 import de.com.baseband.client.feature.modules.render.SwingSpeed;
-import de.com.baseband.client.feature.modules.ingame.AutoSignText;
 import de.com.baseband.client.util.adapt.FieldFinder;
 import de.com.baseband.client.util.net.ScreenshotHelper;
 import net.minecraft.client.gui.ChatLine;

Client/src/main/java/de/com/baseband/client/mixin/mixins/ICPacketUpdateSign.java

@@ -0,0 +1,14 @@
+package de.com.baseband.client.mixin.mixins;
+
+import net.minecraft.network.play.client.CPacketUpdateSign;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+@Mixin(CPacketUpdateSign.class)
+public interface ICPacketUpdateSign {
+    @Accessor(value = "lines")
+    String[] getLines();
+
+    @Accessor(value = "lines")
+    void setLines(String[] lines);
+}

Client/src/main/resources/mixins.baseband.json

@@ -6,15 +6,16 @@
   "refmap": "mixins.baseband.refmap.json",
   "client": [
     "ICPacketChat",
+    "ICPacketUpdateSign",
     "IMinecraft",
     "IPlayerControllerMP",
     "IRenderManager",
     "ISPacketExplosion",
     "ITimer",
+    "MixinEntity",
     "MixinEntityLivingBase",
     "MixinEntityPlayerSP",
     "MixinEntityRender",
-    "MixinEntity",
     "MixinEventBus",
     "MixinFMLNetworkRegistry",
     "MixinGuiEditSign",