SYNVO supports as first TTS engine automatic language identification and a sophisticated, real polyglot speech generation of mixed-lingual texts for a broad range of languages. SYNVO has you covered with any mixture of 20+ languages including

Mandarin (China) Italian
Czech Japanese
Danish * Korean
Dutch Norwegian *
English (UK) Polish *
English (US) Portuguese
Finnish * Portuguese (Brazil)
French Russian
French (Canada) Slovene *
German Spanish
German (Austria) Spanish (Mexico)
German (Switzerland) * Swedish
Greek * Turkish
* … language in development