What gets registered with ISC is the transfer document itself, signed under the authority a power of attorney grants, not the power of attorney document as a standalone filing on the property's title history.
That does not make the review optional. A lawyer who registers a transfer without confirming the power of attorney is valid, current and broad enough to cover a real property sale is taking on real liability, typically as part of the same $800 to $1,500 in legal fees a Saskatchewan closing already carries.
Keep the original document with your lawyer's file rather than assuming it travels with the title, since it does not. Get your hand-reviewed valuation from Joel Dyck.