When placing a Real-Time Text call, once the braille user enters the area displaying what the other party is typing, the text will not update with the newly typed text. The braille user will only be able to read what has been typed before they enter that text area.
The only work around is to leave the text area and then return to it and scroll to the newly typed text. Alternatively, the user may disable the "send immediately" option under Settings>General>Accessibility>RTT/TTY and toggle this setting to "off". However, it's worth noting that disabling send immediately can sometimes cause issues when calling a TTY such as those systems found at 911 centers.