I didn't submit my form but did make a mistake; I wrote my date of birth wrong. Will they accept having a crossed-out date of birth and, written above in black ink, the correct date? I live in Saudi Arabia
Anecdotally, I can say that yes they can.
I applied for a UK visa a few months ago, but got the month and day of my birth date mixed up (me getting confused with the American way of MM/DD/YY instead of DD/MM/YY)
My mistake was noticed when I went to my biometric appointment when the technician noticed the discrepancy between my application and my passport.
She corrected it on the paper form and I signed next to the correction and, probably most importantly she corrected it in their online system right then & there.
So if you make the correction on your printed form - make sure you bring it to the attention of the person taking your biometrics so that they can make the online correction too.
This was in Atlanta, GA, USA though, so I don't know if this is official policy worldwide or not.
Usually agencies will accept small edits in forms. But best edit it with white correction ink, such that it stays machine readable. But if you are unsure, why don't you find the form online and fill it out again? Nowadays there is no such thing as only accepting the original printed paper (there was a reason this was commonn in the early days of machine scanned form, where there were invisible markings). Just make sure the orgininal text is unreadable as a half readable text will confuse text scanning software.