Hello Sivahari
Good Day!
1.- I could say no, the ABIST covers the short-to-high on RSTB, but it's not immediate since it monitors multiple voltage levels. Therefore, it's safe to say that it performs the monitoring after the 300µs it takes the ABIST to complete the monitoring.
Therefore, the RSTB release once the ABIST is done
2.- Yes
3.- RSTB_EVENT bit reports an activation of RSTB pin
I recommend that you review the safety manual and the full version of the datasheet found in the secure files of our FS26 page for more detailed information.
I hope this information has helped you, please let me know if you need help with anything else.
Have a great day and best of luck.