in TranslateEng, made vocative possible both before and after the phrase. Should be so in other languages as well. There should also be an optional comma, but this is not right if the vocative is empty - which means that empty vocatives are probably not the right thing to have

lib/src/translator/TranslateEng.gf

@@ -21,7 +21,9 @@ concrete TranslateEng of Translate =
     ComplVS, SlashV2S, ComplSlash -- Eng exceptions
     ],
   AdverbEng,
-  PhraseEng,
+  PhraseEng - [
+    PhrUtt    -- (but come here John) replaced by (but come here ,? John | but John ,? come here)
+    ],
   SentenceEng - [
     UseCl     -- replaced by UseCl | ContractedUseCl
     ],        
@@ -47,6 +49,13 @@ flags
 
 -- exceptional linearizations
 lin
+  PhrUtt pconj utt voc = 
+      G.PhrUtt pconj utt voc                                   -- but come here John 
+----    | {s = pconj.s ++ utt.s ++ Predef.BIND ++ "," ++ voc.s}    -- but come here, John  ---- comma with empty voc is bad
+    | {s = pconj.s ++ voc.s ++ utt.s}                          -- but John come here
+----    | {s = pconj.s ++ voc.s ++ Predef.BIND ++ utt.s}           -- but come here, John
+    ;
+
   UseCl t p cl = 
      G.UseCl t p cl              -- I am here
    | E.ContractedUseCl t p cl    -- I'm here