The Hebrew calendar is "off" by
as much as 256 years.
The following is an older article explaining:
"The Jewish Calendar: What year is it, and does it really matter?" - Dr David R Reagan
The Jewish Calendar | Jewish Life | Lamb and Lion Ministries (christinprophecy.org)
[quoting from article] "That brings the total difference to 256 years!"
In view of this study, I do not believe that
"5758" is the actual current year.
[
and for the readers: the "1260
days" the "1290
days" and the "1335
days" should be understood as "days" and not "years," in their contexts where these are mentioned
]