I would agree that you will need to accomplish the IPC unless you have continually remained instrument current as defined by 61.57 (c)(1) since your last check by an FAA authorized individual. If you were ever more than 6 calender months out of IFR currency during that period, then I would say you need the IPC to regain currency under FARs. While time flying other than US registered aircraft may be logged and the experience credited toward any experience required to meet any FAR requirements, it appears that training and checks only count if given by FAA authorized individuals.
See the rating task table on page 16 the instrument
PTS (.pdf unfortunately.) to find the TASKS required to be completed in order to accomplish an IPC.
Best regards,
Westhawk