I haven't read your purchase contract, but in general if it's in the contract, the underwriter is well within her rights to ask for proof that it happened or is happening.

Unless your lawyer is a licensed loan originator, your lawyer isn't qualified to have an opinion on the matter.

Experienced Realtors, who are far better than typical lawyers a keeping transactions smooth, leave things off of contracts all the time, specifically for this reason. Most commonly, a lawyer will write "seller to credit buyer $5k to fix the plumbing" into a contract, opening a can of worms with underwriting, and a Realtor with 10 minutes of experience will write "seller to credit buyer $5k towards buyer's closing costs," and things sail to closing without issue.