if taking a title proper from OSoI (because no title is provided within the resource itself), then enter the Title Proper without square brackets and add a Title Source note to explain the source
data for this element must be Transcribed, but 1.7: the data must match word-for-word and letter-for-letter (except for exceptions, error or old cataloging rules)
if data is given in square brackets, it is 'supplied' data, and comes from outside the resource itself, and so can be accepted as given, for matching, as long as it seems reasonable for the resource
since this type of data is supposed to come from a specific source, it is not ok if the data cannot be found on that source (except for error or special instructions for the element)
but be sure to check the resource carefully, if the data for the element is Core, or if the data is important for differentiating the resource from a similar resource