The CO2 in the water would be treated with an automatic neutralizer tank. Sounds like the pinhole leaks could be caused by other factors such as water velocity through your plumbing. Post a question to this forum about what causes pin hole leaks in copper pipe. This has been discussed in great detail before in here and someone may have saved some of those replies.
On private water systems, the most common cause of corrosion is from low pH (acidic – less than 7.0 pH) waters. Often these waters are of high quality and are low in buffering calcium minerals, but are high in dissolved carbon-dioxide gas or CO2, this can cause the low pH or acidity. Treatment is accomplished by neutralizing the water with an automatic neutralizer. These water filter tanks are filled with a blend of calcium and magnesium carbonates made from naturally occurring minerals, which dissolve into the water, making it less corrosive. Other methods commonly used are pH adjustment by injecting soda ash or a sodium hydroxide solution into the water upstream of a holding or retention tank.
Respectfully David F. Walling