They should be consistent. Sadly, because this is a wiki and not any kind of proper database content management system, keeping any kind of consistency is very hard.
There isn't even a proper template page that would have the definitive format so the best that can generally be done is look at a bunch of pages at random to see what is used most often.
This is system dependent. Mine does not show the AM/PM, and shows it in 24 hour mode, because that is what my system is set to.
I'm not sure what the original page said, or whether there was ever a change to this. IOt's probably always been system dependent.
Yes it is.
Without looking at the original text, I'm not sure, but generally, no, the wiki should not be referencing "My" anywhere.
OK, I went and looked at the original page, I believe the statement was simply explaining the image shown’s lack of an AM/PM indicator. It was written in 2008 - almost two decades ago and has remained unchanged since then.
The statement should have been written in the impersonal and referenced the image, something more like "The image does not show an AM/PM indicator only because the system on which the image was captured was configured to 24 hour clock". Something like that anyway.