Coffee grounds aren’t very good fertilizer, they still need to decompose. Better to mix them in your compost pile and wait til the compost is finished to use it.

Regarding acidity, like the other guy said, used grounds aren’t very acidic. But ultimately, the pH question is going to depend on lots of factors, including the pH of your existing soil and the optimum pH of the plants you’re growing. Sometimes you want to add acidic amendments. Where I live, there’s so much calcium carbonate in the soil, no amount of acidic compost would even make a dent in the pH