I've talked to a ton of lenders and if they know it's an investment property, you're looking at 15-20% down minimum (non owner occupied).

Rather than use credit score as a criteria, I reject for consumer accounts in collections and unpaid civil judgments.

Check with your lender to make sure you heard it correctly. 

Btw, the buyer is in no way at any criminal risk vis a vi the lender, he has no contract with the lender and therefore no obligation to the lender.

I've used the search feature on this forum but didn't have much luck.Are there any US investors, hard money lenders, or groups that invest in flips outside of the United States, specifically in Europe (Netherlands, Spain, etc.)?

If she went to buy a house and applied for a mortgage, I think the lender would say the same thing aka you don't qualify until you get this removed from the credit report.

Any investor-friendly lender and/or agent recommendations in this area?

WIth the new FHA & Fannie Mae legislation, many lenders are forecasting the rental income from additional units, even if they're not a zoned duplex.

Just to clarify, when I say timeline dates I don't mean just "project to be completed by (Date)"That's required by FHA/Lender, but in my 20 years of construction experience not nearly what you need haha. 

Start running numbers on potential deals to get more comfortable, and build out your team—like a CPA, property manager, and lenders.