Set alphabet=latin (uroman output_alphabet == input_alphabet)

facebook__mms-tts-tir-Tigrigna/config.json

@@ -2,7 +2,7 @@
   "phoonnx_version": "1.0",
   "engine": "transformers",
   "phoneme_type": "uroman",
-  "alphabet": "unicode",
+  "alphabet": "latin",
   "lang_code": "ti",
   "audio": {
     "sample_rate": 16000