How can I improve the phrasing of the voices? (Text to Speech)
You need to break the rules of punctuation that you learned as a child, and refined as an adult. Ignore them, throw them away .. your focus becomes "how does this sound"?
Punctuation forms
When providing the EN or EN2 messaging (for English) you can start with common use of punctuation. However, when you proceed to the stage of listening to the messages, as they are translated from text to speech, know that the placement of commas can help the "listenability" of the translated text.
An example
Instead of writing "When entering the elevator you will find the controls in two columns on the right" you can improve "listenability" by expressing the text as "When entering the elevator, you will find controls, in two columns, on the right"
In some presentation forms you can include multiple commas, to prove a longer pause between words. This can help bring focus OR improve comprehension of the message.
Voices~
When shaping the delivery of the voice messages remember to consider the lowest common denominator. Many BlindSquare users chose from the bounty of Acapela voices, for fun, for clarity or for differentiation providing BlindSquare - a unique voice. The interpretation of punctuation in the construction of the voice-message can vary from voice to voice. The recommended course is to limit yourself to simple punctuation changes and use the iOS voice for review. Any punctuation changes that improve the speech for the iOS standard voice, will also improve the delivery for those making use of Acapela voices too.