French/most compatibile desktop software solutions:
"Solegis Pro is particularly suitable for self-employed entrepreneurs providing specialized services to individuals. This freeware allows you to manage key aspects of your business: sales management (products, customers, sales documents), purchases (suppliers). It includes a financial dashboard displaying the monthly, quarterly and annual turnover." -source
"TerCompta offers custom features to meet the needs of self-employed entrepreneurs. This is accounting solution for small businesses, artisans and self-employed entrepreneurs. It meet the needs of simple accounting." -same source
Laurux appears to handle contact management, scheduling, taxes, bookkeeping, and invoicing.
Laurux is for Linux. I'm not sure about the first two. The rest of these will run on a Mac:
Busy Bee Invoicing features client and project management, invoicing, time tracking, multi-currency, and multiple languages. Demo version available. $20.
iCompta is a personal finance manager for tracking income and expense accounts with professional features (client management, invoicing, scheduling, taxes) that's localized in English, French, and Italian. 30day free trial. $30.
Vosae is based in France, still in beta, and features: timeline, contacts, organizer, and invoicing.
Banana Accounting is a spreadsheet-based system: income & expense, double entry, multi currency, multi-language, reports, taxes, etc. Trial version has a 70 transaction limit. ~$137.
Other desktop solutions:
There's also Oranged Software's Studiometry Express for project and client management and invoicing ($100) and Accounted for full featured double-entry accounting and reporting ($80). iCal and Address Book integration; multi-currency support. 30day free trials.
If you need more customization & flexibility, there's Kedisoft's Totals 3 which is listed at $150 on the App Store and $129 on their website plus a 25% offer ending soon so you can get it for ~$97 now if you do so from Kedisoft directly. Another of theirs you may want to look at is Invoice, which is a less powerful Totals that goes for $40 on their site as well as the App Store. 30day free trials.
Two others that handle bookkeeping and invoicing with multi-currency support are Nano's Accounts ($30; also integrates with Address Book) and Luca by CutEdge ($10).
Wave Accounting for invoicing and bookkeeping supports multi-currency (ad supported freeware). For client management ClinchPad, Insightly, and Really Simple Systems all have decent free plans.
Phreebooks is an open source ERP application meant for small businesses. All-in-one solution but might be a bit overkill.
Lastly, Zoho has modules for just about everything. Pricing is per month, free trials are available, and some have limited free plans.