Further observations, following additional tests:

1) The fact that I obtained the same behaviour both in backtesting and live is due to the fact that I indicated an updated Oanda asset list in the z.ini, making the strategy ignore the Assetsz6.csv (in which PIPCost and Multiplier are obviously not consistent to the Oanda asset list).
2) It looks like PIPCost and LotAmount would need a correction if trading Z6+ on Oanda (API), which I understand would not be possible unless changing the Z6+ source code (SET_PATCHing or similar), right?
3) I believe that applying a 1000x factor to Capital could represent a workaround at this stage.