A GREIBACH normal form for a superclass of CFTG (viz., second-order abstract categorial grammars) was discussed by Kanazawa and Yoshinaka (2005) and Yoshinaka (2006).
they also demonstrate that monadic CFTG can strongly lexicalize regular tree grammars (Gécseg and Steinby, 1984;Gécseg and Steinby, 1997).