Neat. I've never seen that chart; that's kind of fun! And it does answer for you how often the string gauge changes -- the breaks in tension vs. note give it away.
From a rather general point of view, different gauge strings for the same note (therefore either different tension or length) do make a significant difference in tone, particularly if it is the length that is changed. The reason is the stiffness of the string itself, which is not negligible. A stiffer string (larger gauge) theoretically should have less power in the higher harmonics than a floppier one, up to a point. This is also, however, very much affected by the exact location along the string that it is struck by the hammer.
Not a techie, but I am a little nerdy.(Or am I flirting with you? who knows!)
Anyways:Depends, are there sets of 2/ sets of 3 unisons and how many? each piano is different. I am pretty sure that the gauge is not changed across each string in sets of 3(uncoiled) and sets of 4. a4 is string no 49...so that would be what I would google. The tension for a4(why don't you just give me a length of the 1st string and the a4 string you need to gauge/add tension?) I am going to calculate that and respond back to you today(please, do I have to?)
however, as the pitch increases, the gauge and length slightly decreases, so perhaps the tension on each string is actually the same! (it depends on your piano how many rotations of the tuning peg it takes to achieve specific frequency)
Measuring my own piano, I believe the speaking length is ~15.5" (rough guess without shoving a tape measure between dampers), @440hz and 198.5lbs tension is a #19 gauge piano wire. But if it's widely variable, then I'd be better off just doing it from scratch.Another thing that popped into my head was spacing between the voicing strings. So within a 3-string note, would a gap of 2mm betwee each of the strings differ from a gap of 4mm assuming they were still struck equally?