GC filing clarification


My husband is currently on H1B and is working in USA. They r processing GC in his company. He is having around 11 years of experience. Now the question is : they are asking my husband’s service letter from each of his previous company in a format which mentions his duties and responsibilities. His first employer does not include his training period in his service letter. But all his previous visas(L1B & H1B) has his training period of 4 months in his profile.

Now, if he removes that 4 months from his total work experience will it be a problem at USCIS. In case it is a problem, could someone suggest an idea.