Unfortunately, no. None of those is Fleener's. I have grown, or are growing, many of those. Caudell, Comstock, and Knox (I have abreviated all of those names) were the three topsets I lost to flooding; all are similar to Catawissa. Neither have I observed Fleener's growing in their perennial allium plot during my annual visits... and I
have been looking for it. If SSE had white bulbed multiplying onions other than McCullars, they were either dormant (and hidden) or had already been dug.
The onion listed as Fleener's in the Yearbook is an imposter, as verified by myself, and the original source (IA AR W). It appears to be McCullar's, or something very similar.
I concur with Kaz's description of the differences between McCullar's and Fleener's. I would add that for me, the topsets of Fleener's were larger, and slightly flattened. Fleener's also seemed to be less winter hardy than McCullar's, I lost a few the first year... then lost them
all to voles the second year.
It is worth pointing out that McCullar's is not a bad onion. The clump in my perennial garden forms nearly round, white bulbs about 1" across. That soil is not the best, so I Fall planted a few topsets along with my garlic, in much more fertile soil. This was the result:
The bulbils in the lower left are similar to what I planted. They grew not only fairly good sized bulbs, but larger topsets - in the first year - than what I planted! I tested those bulbs for storage life, though, and while they don't deteriorate as fast as Catawissa, none of them made it to Spring.
I have a larger planting of McCullar's currently growing in my garlic bed, I hope to test their culinary qualities this year.