How can I reduce the richness of my homemade chocolates?

What you are using is not chocolate in the strict sense, it is a highly engineered product made to be easy to use by the home cook and taste similar to chocolate. I would advise against adding anything - this kind of product has been balanced by armies of food technologists to behave just like it does. If you start changing it by adding stuff, you will probably start getting trouble using it (e.g. it could curdle, or start sticking onto the molds, etc.) or the final texture will be weird, or both.

If you want to keep the ease of making your molded chocolates, you can just switch brands of mold-intended chocolate product, until you have found something that the eaters enjoy. Alternatively, you can get into standard chocolaterie, where you have limitless options. It will however require the committment to learn how to do it properly, to invest in tools and ingredients, and to find out which recipes you and your giftees like. If you can imagine developing a pasion for that, go for it! Or if you are unsure, try a simple tempering once or twice and see if you feel drawn to getting it right and delving deeper. If not, the premade products you are using are your better option, even though they cannot be personally tailored to people's tastes.