using the mazda FL22. I took the under cover off a few months back, and don't see any leakage.
it is difficult to read the tank. I can smell burning coolant - so it is going somewhere.
prolly weeping onto exhaust manifold somewhere; oil level will INCREASE if it's ending up inside the block.
If you've already replaced all hoses AND waterpump, I've had good luck locating TINY leaks by totally emptying all coolant (including block), then pressurizing to 15/20 #'s with AIR, then listening around for HISSING sound - head cracks/gasket leaks are revealed by removing plugs and listening inside spark-plug hole (use a rubber tube - one end at ear, other in plug-hole, or anywhere leak suspected.