lightbright – after lighting candles is definitely a time to direct prayers to Hashem regarding anything in your heart. If you want to bless people, it would be appropriate to use that time to ask Hashem to Bless them. It is a time to speak to Hashem.
Regrading lighting a candle, the candles are Shabbos candles. There are halachos and minhagim about how many and for what reason but I am sure that lighting them randomly for different people or families to bring them blessing or feel connected is not an appropriate use for this time. I have strong doubts that lighting a candle for someone as a blessing or kind thought is a Jewish concept at all (excluding yahrtzeit). Furthermore, if you light a certain number of candles for shabbos, there may be a serious question on whether or not you can stop lighting that number.
mixing in “feel good” actions with halachos (lighting a candle to connect to someone) can be very serious and I think that is what the rebbetzin responded to. knowing it was not your intent and where you were holding may have made it difficult for her to digest and explain.
I have a cousin into the kabalah institute r”l. they leave water bottles out during torah reading of certain parshas to “absorb the holiness” of the torah reading and then use that to elevate themselves. It may sound spiritual and feel-good-ish but it is not dictated by Torah to do so and therefore is potentially dangerous.