Let me see if I understand this. Your DD is in a facility where she is happy, safe, well cared for, and part of a program of which you approve. Her care providers are so discreet and circumspect that you, an adult, cannot ascertain their sexual orientation. But you believe that IF they are lesbians that your two-year-old MIGHT witness an innocent display of affection and that, by being exposed to two adults exchanging this affection, she would be harmed in some way.
I don’t know what your work history is, but in the forty-some years I worked I never saw two married professionals hold hands, kiss, or show any physical affection for each other. Extrapolating what you and your DH do at home in your non-working hours to how two professionals act toward each other in their business environment is illogical to me.
On the infinitesimal chance that your DD did see a brief kiss, I doubt that she would even notice it. We often kiss our friends, male and female, in greeting, and I do not remember ever giving it a thought as a child nor did my DD even seem to notice. As for holding hands, when would two people who are taking care of a room full of little ones ever have their hands free long enough to do that?
She is your DD and you are, of course, free to raise her as you wish, but in our changing world it is almost inevitable that she will see same-sex couples acting affectionately toward each other. I would doubt, however, that two people whose livelihood depends on having people feel comfortable with the environment in which their children spend a good part of their waking hours would be likely to do anything to destroy that comfort.
And please do not ask about their sexual orientation, no matter how subtle you think you are being. If they are lesbian, it will be all to apparent what you are doing and it is beyond rude. Their conduct may be your business, but their sexuality certainly isn’t.