The xsettings_callback is ignoring cursor-size changes since there's not translation entry for this key - it is supposed to be handled by xfg_callback, but we're not calling it :-(

This should fix it: 

@@ -1033,7 +1033,8 @@ xsettings_callback (GSettings             *settings,
         GVariant         *value;
 
         if (g_str_equal (key, TEXT_SCALING_FACTOR_KEY) ||
-            g_str_equal (key, SCALING_FACTOR_KEY)) {
+            g_str_equal (key, SCALING_FACTOR_KEY) ||
+            g_str_equal (key, CURSOR_SIZE_KEY)) {
                xft_callback (NULL, key, manager);
                return;
        }