Can I configure the PWD/OTP screen text or Mobile ID text?

Yes, as described in the All-in Signing Service Reference Guide under "Step-Up method" in the "Message" field. You can configure the text block with the heading to the message for the expression of intent and the language setting with "Language within the protocol framework. Additionally, you can set the "language" parameter for the SMS input window.

In case you are using the Multiple Authentication Broker (MAB) you will find the adaptation of the workflow text in the content of the CIBA description.