Reservation is required but full, is QR ticket enough?

So if I understand correctly does it mean even if I have received qr ticket but haven’t reserved the required seat as there is bo more available . My current qr ticket doesn’t valid?

Yes, if you don’t have a reservation you won’t be able to travel on those services.

For Paris - Amsterdam the alternative is TGV to Lille, book here https://travel.b-europe.com/eurail-ge/en/booking-tgv?

Then non-reservable trains from Lille Flanders (TGV may arrive at Lille Europe which is less than 10 minutes walk away) with several connections via Antwerp which run hourly.

Your QR code is day specific, not train specific so you don’t lose it. It is valid on any train you travel on in that day as long as you record it on the app before boarding. So all you need to do if you find an alternative routing is remove the direct train and add the new trains before you travel.

Reservations are separate from your pass and, as you have just found out, need to be made separately for any train you want to travel on showing in the planner (or App) as being mandatory.

If you are now not travelling on that day you can remove any and all journeys for that day (before midnight CET of the previous day)  and the App will automatically add that day back into your still available days.

As @Yorkie says, the advice from the experienced travellers is to never create the ticket for a journey until just before boarding the train. If you have a flexi pass you may loose travel days. Please read more below. 

Here is some useful information from the experienced travellers in the Community regarding both planning, reservations and activation of pass and travel days. 

 Planning

The rail planner is normally not up to date, as it only is updated once a month, so to be sure of the time table you better check the timetable and availability on the websites of the national railways. The bigger national railways, like DB (Germany) SBB (Switzerland) and ÖBB (Austria) cover several countries. 

 Reservations