I think your confusion is catching as I don’t understand why you created the 192.168.224.x subnet on your site when you already had the 192.168.0.x subnet. The VPN would work better if both sites had different subnets and sent traffic between the hosts on the subnets across the VPN tunnel. Traffic not destined for the other site would then go out a non-VPN route to the ISP’s network.
So, let’s say that the Spain network is the 192.168.224.x network and your network is the 192.168.0.x network. Traffic going to a device on 192.168.224.x network would go to the default gateway on your LAN and then get routed across the VPN tunnel. Any traffic not destined for a 192.168.224.x device would go to the internet. Devices on each network would be able to talk to each other without going to the gateway if the subnet masks are correctly set at each end. In this case a 24-bit subnet mask (255.255.255.0) would be recommended.
Hope this helps and if not maybe you can provide more details on the reasoning for the current double IP address configuration.
Since you have two IPs per device, all devices want to only use the primary IP which would be the 192.168.224.x subnet. That means everything is routing to the Spain DSL gateway. To make sure only traffic meant for Spain is sent through the Spain gateway, you need to change the default IP route on the 192.168.224.x gateway or switch to point to your local gateway. Then set a static route for traffic going to the Spain IP address to point to the Spain gateway.
Say Spain’s internal network uses 10.0.0.x. You need to set a static route for all traffic going to 10.0.0.x to 192.168.224.1. And set the default route (all other traffic) to use 192.168.0.1.
Adding just two static routes will prevent you from changing anything else.