I don't understand what you think the relevance of that is to the effect foreign buyers have on house prices.

The house market is split between people buying and renting. When people buy as an investment, it does drive up purchase prices, but unless they leave it empty rather than rent out, it drives down rental prices by increasing supply. Rental properties also tends to provide more density, as they are more likely to be occupied by sharers, and so increasing the rental supply is likely to soak up more demand than the reduction in purchase opportunities. Eventually the prices reach some degree of equilibrium, because bidding up the purchase prices much quickly becomes unprofitable as rental prices are pushed down.

Ultimately what is driving the cost up is mainly down to more people with enough money who wants to live in a given location, not investors, as if there wasn't demand to live there it'd quickly prove a bad investment.