By water proofing the inside foundation your looking for major problems as your forcing the water to seek other voids in the foundation wall and then the erosion can occur.
Personally is possible I would let the water continue to come in where it can be controlled.
Last summer we just completed a one family home that had a severe water condition (condition is where there is no cure) and water proof the entire out side wall after digging up the foundation and installing the JR grace membrane. It cost the home owner just over $625,000. You can try to get either a water proofing contractor OR a water proofing engineers opinion. Good Luck