Qn Contingent worker invoice in different currency to Labour Cost currency asnd project currency?

Scenario I have is a contractor (contingent worker) who is from a US Company is working on multiple projects in the UK of which the projects are defined as GBP projects and EUR projects.

His Labour Cost for a Contingent Worker is defined as a GBP hourly rate. Via OTL he records his hours for project A (GBP defined) A and his cost is recorded in projects in GBP. He also records timeon a EUR project 2, his cost is converted into EUR.

If this contingent worker then invoices in USD, splitting his hours per USD rate to the project, can someone explain the accounting for this as I can't understand how this will not create reconciliation/ gain & loss issues as the supplier invoice in USD will be converted to GBP on invoice FX rate and his cost will have been recorded at a different rate in projects from OTL?