Flex-plate does it need to mesh completely, or is it normal not to fully mesh

To outline the question, and give the complete history, my flex-plate failed in 2012 at 100,000 miles. The plate had broken away, approx 1"to 2" outside the circumference of the attachment bolts, The flex-plate was replaced with a Pioneer plate. It has performed flawlessly, until I recently experience an engine lockup, and two teeth on the ring were broken away. I had a terrible time finding a listing for a replacement, and ultimately settled on purchasing two, and then checking for proper fitment before installation. I purchased a NOS Ford plate, that was listed as fitting the 1996 to 1998 year model Windstar with a 3.8 The other was listed for a 1995 Windstar, and was a NAPA brand. I settled on using the NAPA plate, as teeth to mount surface measurement, aligned with the plate that was removed. There was an 85 thousandths difference, when measuring the Ford plate. Because it was not specifically noted as fitting a 1999, I opted not to use it because of the difference. I am now finding, that the starter gear is not fully meshing with the flex-plate teeth, and the question is, does it need to mesh completely, or is it normal not to fully mesh? Looking at wear on the starter gear, it is meshing about.320" of the.375" tooth width. In studying the Pioneer plate that was removed, I could also notice a wear line close to the.320 engagement, and seemed to work fine since 2012.