Your first screenshot has the answer in it. The Optimization Matrix core world line and the Optimizers line are the same percentage, and the Optimizers one is per ship. Park a second one there and you add that percentage again, with nothing capping how many you can station.
The matrix cells are not what stacks. Inside a row only the highest cell you own counts, so owning I through VI gives you the VI value rather than the sum, with an extra multiplier for completing the row.
So the runaway is the ship stack rather than the matrix itself. An uncapped per ship multiplier is worth a bug report.