@Anonymous Azure translator service has an API for transliterate where one script is changed to another without changing the pronunciation in English. However, this API does not support Pashto for transliteration. Other languages like Arabic, Hindi, Punjabi & Urdu are supported. This might work with some scenarios with Urdu but not completely.
The Language studio feature to train a model using conversational language understanding(CLU) supports Pastho language but not with text written in English (Latin script). You will have to use Pastho if a project is created with Pastho.
Using English as project's language to train a model for Pashto will also not work because the base models are trained in English and Pastho text in English will not be recognized/trained correctly.