run textcomponenttranslations through the ForgeI18N message format translator as well.

patches/minecraft/net/minecraft/util/text/TextComponentTranslation.java.patch

@@ -0,0 +1,13 @@
+--- a/net/minecraft/util/text/TextComponentTranslation.java
++++ b/net/minecraft/util/text/TextComponentTranslation.java
+@@ -101,6 +101,10 @@
+             }
+          }
+ 
++         if (j == 0) {
++            // if we failed to match above, lets try the messageformat handler instead.
++            j = net.minecraftforge.fml.TextComponentMessageFormatHandler.handle(this, this.field_150278_b, this.field_150277_e, p_150269_1_);
++         }
+          if (j < p_150269_1_.length()) {
+             ITextComponent itextcomponent1 = new TextComponentString(String.format(p_150269_1_.substring(j)));
+             itextcomponent1.func_150256_b().func_150221_a(this.func_150256_b());

src/main/java/net/minecraftforge/fml/TextComponentMessageFormatHandler.java

@@ -0,0 +1,18 @@
+package net.minecraftforge.fml;
+
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TextComponentString;
+import net.minecraft.util.text.TextComponentTranslation;
+
+import java.util.List;
+
+public class TextComponentMessageFormatHandler {
+    public static int handle(final TextComponentTranslation parent, final List<ITextComponent> children, final Object[] formatArgs, final String format) {
+        try {
+            children.add(new TextComponentString(ForgeI18n.parseFormat(format, formatArgs)));
+            return format.length();
+        } catch (IllegalArgumentException ex) {
+            return 0;
+        }
+    }
+}