Load balancing gateway group without NAT

[senseivita]

I have a remote gateway with two public addresses, IPv4.

Remotely, each of those addresses has its own interface with its own bandwidth allocation, which if aggregated is still less than my single local link to the Internet. Thus, attempting to get the most out of them I set up two VPN links to loosely aggregate their bandwidth via ECMP.

Remote router/gateway

Neighbor ID     Pri State           Dead Time Address         Interface                        RXmtL RqstL DBsmL
1.0.0.1           1 Full/DROther      36.236s 192.168.91.1    ovpns1:192.168.91.0                  0     0     0
1.0.0.1           1 Full/DROther      36.235s 192.168.92.1    ovpns2:192.168.92.0                  0     0     0

Local router/gateway

Neighbor ID     Pri State           Dead Time Address         Interface                        RXmtL RqstL DBsmL
4.0.0.1           1 Full/DROther      34.164s 192.168.91.0    ovpnc1:192.168.91.1                  0     0     0
4.0.0.1           1 Full/DROther      34.165s 192.168.92.0    ovpnc2:192.168.92.1                  0     0     0
1.0.0.2           1 Full/DR           37.618s 10.190.0.3      vmx0.190:10.190.0.1                  0     0     0

There is no [double-]NAT happening between routers anywhere, all NAT occurs only on interfaces with public addresses and in some 1:1-natted VIPs (to split and recombine rev proxying and other data streams), so traffic routed to the remote gateways keeps its source address all the way until it's about the exit to the public network.

In the remote gateway each of the tunnels' incoming traffic, has its own gateway assigned, opposite to the tunnel the traffic came in, unless it's initiated from outside (port forwarding) then it's straight-through all the way. it's sent to a VIP in the local gateway with the route decided by the routing protocols.

Lastly, as I mentioned already, aided by FRR/OSPF, ECMP routing is active between sides, which is where my question stems from since I think it might conflict with this as traffic seems already lossy: can I set a load balancing gateway group without NAT in the LOCAL ROUTER using the tunnels?

I don't quite understand or know if (and how) the visibility into the network from the other side might prompt it to return the traffic through the other tunnel, and not from the one it was sent, and what that might cause. Just in case though, I enabled the static route filtering option in the local side:

I tried to make a drawing to illustrate all of this but it's kinda complicated, and on the third draft I still can't get it simple enough. Here's… something:

Should I remove the LB gateway group, and perhaps set a gateway on a virtual IP on the remote side, or on the interface on the remote side, or something like that?

Thanks.