Confused CWI:
You are experiencing the growing pains all fabricators are going through since the FEMA 350-353 docs. were issued. Pleae note these are only "recommendations". If D1.1 is specified, then section 5.10 applies.
Many engineers here in CA tried a few years ago to put vague wording such as "...comply with FEMA requirements", or, "...and per FEMA 353...". This came back and bit them in their hind quaters when inspectors and fabricators said: "OK, which part?" This usually left the RDP at a loss for words and then tapping the mat and: "Remove bottom backing bar only..."
The bottom bar is critical to the performance of the MF conection, so many have adopted removing bottom backing w/a reinforcing fillet weld (3/8"). FEMA recommendations have been incoporated into the Los Angeles MF criteria about to be released and presented in March including the backing bar removal and finishing.
Most fabricators have moved on beyond the 1st few jobs where FEMA was not inclusive to the bid. Even other postees here note they now are cognizant of the specs. Now most seasoned fabricators here know to add some $ to the bid for additional work not required in the past including additional procedure and personnel qualifications, orienting the material grain, backing, deposition limitations, etc., etc.
Good Luck.