Yes, there's an FX conversion if you're selling in any currency other than USD even if your client is making a purchase in the same currency that the solution is being sold in. An FX conversion from non-USD local currency to USD occurs for all pricing at point of saving in Partner Center.
Conversion from USD to Euro will be done upon first saving of the plan price based on the current monthly FX rates.
You can edit the local price in EUR through the Export pricing data Excel spreadsheet to avoid further currency conversions.
Where the customer’s billing account, and publisher’s payout currency are the same, no other FX conversion occurs for the customer.