Does TitleLeaf store a trade announcement date?

No, TitleLeaf doesn’t have a trade announcement date field in its database. As an opinionated implementation of ONIX, TitleLeaf can derive a trade announcement date from the public announcement date of a given product format on request. When submitting such a request, specify the number of days prior to the public announcement that you’d like the trade announcement set. Acceptable values are 0 to 180 days. This is a global setting, applying to all product formats.

See ONIX List 163: Publishing date role, value 10:

Trade announcement date: Date when a new product may be announced to the book trade only. Prior to the announcement date, the product information is intended for internal use by the recipient only. After the announcement date, or in the absence of a trade announcement date, the planned product may be announced to supply chain partners (but not necessarily made public – see the Public announcement date) as soon as metadata is available