There's not a way to send off a PDF depreciation schedule and get back an importable file with the details.

Assuming it's a reasonably clean scan, I can sometimes OCR the PDF and copy-paste into Excel, and Lacerte has a depreciation import tool that will work with an Excel file. If the PDF isn't good enough to OCR, and most of the assets are fully depreciated, I'll keep the PDF for future reference and enter "Fully-depreciated assets" as one line-item.

If it's any consolation, depreciation is just the worst. Even if you had the other preparer's original software file and converted it, you'd still need to carefully check all the depreciation pieces to make sure the conversion was done right. It looks like it took me a solid hour last week to export, clean up, import, and proof about 60 assets out of a 2020 1065 and into a 2021 1040, all in Lacerte. It's just really time-consuming to get all the little pieces right.