--- a/net/minecraft/server/commands/CommandSchedule.java
+++ b/net/minecraft/server/commands/CommandSchedule.java
@@ -57,7 +57,7 @@
         } else {
             long j = commandlistenerwrapper.getWorld().getTime() + (long) i;
             MinecraftKey minecraftkey = (MinecraftKey) pair.getFirst();
-            CustomFunctionCallbackTimerQueue<MinecraftServer> customfunctioncallbacktimerqueue = commandlistenerwrapper.getServer().getSaveData().H().u();
+            CustomFunctionCallbackTimerQueue<MinecraftServer> customfunctioncallbacktimerqueue = commandlistenerwrapper.getWorld().serverLevelData.H().u(); // CraftBukkit - SPIGOT-6667: Use world specific function timer
 
             ((Either) pair.getSecond()).ifLeft((customfunction) -> {
                 String s = minecraftkey.toString();
@@ -78,7 +78,7 @@
                 customfunctioncallbacktimerqueue.a(s, j, new CustomFunctionCallbackTag(minecraftkey));
                 commandlistenerwrapper.sendMessage(new ChatMessage("commands.schedule.created.tag", new Object[]{minecraftkey, i, j}), true);
             });
-            return Math.floorMod(j, Integer.MAX_VALUE);
+            return (int) Math.floorMod(j, (long) Integer.MAX_VALUE); // CraftBukkit - Downgrade to Java 8 method
         }
     }