This is a common misstatement. Retina is not just about PPI but about PPI and distance from the screen. My 4k 50" TV isn't retina in PPI terms, but I sit far enough back that I can't come close to discerning pixels. See https://en.wikipedia.org/wiki/Retina_display for a discussion of this.
What this means is that whether a screen is sharp enough to be 'retina' is also dependent on distance... a 32" 4k screen becomes retina (can't differentiate the pixels) at about 25 inches (https://designcompaniesranked.com/resources/is-this-retina/).
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The 5k screen WILL seem sharper but it's not a (forgive me...) black and white difference.
This^
But I totally agree with the comments saying that a 32-inches at 2160P (3840x2160) is not going to be a "Retina display" and you pretty much confirm this. Who sits 64 cm (25 inches)+ from a monitor? I just measured the distance I sit from my 2x 34-inch ultrawides and it's about 51 cm (20 inches) and that's my normal sitting position, I happen to peak closer at times as well. Apple's notion about desktop monitors having to be around ~210-220 PPI to be Retina feels about correct and if we use your calculator that should mean it's Retina as long as you stay beyond 41 cm (16 inches) and sitting anything closer than that seems unlikely for most scenarios.