Assuming you go first, the chance to draw a Tears in hand is at 76%. You may drop one Tear, but it's frankly an unnecessary risk. The more you have, the more consistently will you draw them earlier. On that topic, draw chance is exactly why I don't like SoR's. Having to draw a combo reduces the consistency of a counter deck and in this case will inevitably lead to more total losses over a time span.
Your quoted chance of 76% calculates the chance of drawing it in your opening hand. Clearly, you can't use nymph's tears in your opening hand, and don't need it until 2-3 turns later, once you've generated enough water quanta.
After drawing 9 cards, your chance of drawing one of five tears is at 86%, while a deck with six tears is at 91%. If you have 10 cards before having sufficient water quanta, the percentages are 89 and 93, respectively. A difference of 4-5 percentage points.
The reason I'm looking at 9 or 10 cards drawn is that I ran the OP through 10 games and the average turns to produce 7 water quanta was 2.55.
In those 10 games, the OP (as I played it) lost 3 times, two of which were because of not having a steal to play to counteract the lobotomizer. If you compare two steals in your deck vs three steals, and a scenario where you've drawn 10 cards, the odds of drawing a steal goes from 56% to 72%. After 14 cards, those change to 72% and 86%. This is a dramatic change in the area where this deck tends to have its losses.
Wrt your comment about the SOR combo, I think your comment assumes that you have to wait for one before playing a nymph's tear, and/or before using the nymph's ability. This isn't so. You can use your nymph's ability up until you draw an SOR. Also, the Dark nymph is just as likely to have a quantum shortage. So you don't often need the SOR until later in the game, if you need it at all.