Did it still start a new line with that last word? As in, was all the text on one line (trailing off the screen) and that last word still on a separate line?
If this new line problem only occurs with a comma at the start of it, I think your CSV formatting for RTL language is getting incorrectly read by psychopy, so it thinks that the comma needs to start a new line? I am not familiar with RTL formatting but I know this has been an issue in the past.
Maybe @TParsons can shed some light?
One of the other fixes I have suggested in the past for non-standard text formats, is to create the instructions on something like powerpoint (or similar program that you know works properly with your text format) and export that as an image. Then use that image to present your questionnaire prompts.
Issac