EU trademark squatted – our opposition failed, their mark will register soon. We already have ours. Risk?

One more tactic: if you have the funds, consider filing for cancellation of their mark based on bad faith (bad‑faith registration is a ground for invalidation under EU law). Your own registered mark and prior use evidence support that. It will cost some money, but it's a long‑term solution.

Do not contact them first. Let them show their hand. If they ask for an insane price, you can decide later whether to buy or fight. Many squatters will eventually lower their demands when they realize you won't be easily shaken down.

One thing to note: if the squatter's mark does register, they can still try to file a complaint using their trademark number. Amazon's system might accept it. But you can counter with your own registration and prior use evidence. The key is to get your brand registered in Amazon's system first – that makes it harder for them.
Also, if they're a professional squatter, they may have multiple applications. Don't assume they'll give up easily. But your own registered mark is a strong shield.

A few extra points:

• Use evidence – Gather any documentation showing you used the brand in EU commerce before the squatter's filing date (e.g., orders from EU customers, invoices, shipping records). This is crucial if they ever file a complaint.
• Build a defensive website – Create a simple standalone site showing your product with the brand. If they try to claim ownership, having an independent web presence helps.
• Prepare invoices – Keep 90+ days of invoices for your products. If they file a false complaint, you'll need them to appeal.
• Watch your other markets – Check Germany and the UK separately. Those are hotbeds for squatting.

If the squatter is purely after money, they'll contact you after their mark registers (or after they successfully take down one of your listings). Don't panic – you have your own registration and can appeal. Only negotiate if the price is reasonable.

Using a buyer account for brand registry works fine. Then authorize to your main account. Your US trademark is separate – no conflict.
If both marks are identical in name and class, and you already have a registered EU mark, the squatter's application might not even proceed to registration. Even if it does, they could still try to file a complaint. But because you have prior use evidence (your US sales that shipped to EU customers before their filing date) and your own registration, you have strong grounds to appeal any Amazon complaint. Amazon doesn't always respect regional boundaries, but with your evidence, you can fight back.
I'd recommend not contacting them first. Let them make the first move. If they're just trying to extort, they'll reach out after their mark registers (or after they try a complaint). Keep your cool.