Thanks for the reply, but I think I found the solution.
This is my working configuration:
/ip vrf
add interfaces=ether4 name=vrf50
add interfaces=ether2 name=vrf30
add interfaces=ether3 name=vrf40
/ip address
add address=10.2.4.1/24 interface=ether1 network=10.2.4.0
add address=192.168.1.1/24 interface=ether2 network=192.168.1.0
add address=192.168.1.1/24 interface=ether4 network=192.168.1.0
add address=192.168.1.1/24 interface=ether3 network=192.168.1.0
/ip firewall mangle
add action=mark-connection chain=prerouting connection-state=new dst-address=\
10.2.30.0/24 in-interface=ether1 new-connection-mark=from-main-to-vrf30
add action=mark-routing chain=prerouting dst-address=10.2.30.0/24 \
new-routing-mark=vrf30
add action=mark-routing chain=prerouting connection-mark=from-main-to-vrf30 \
in-interface=vrf30 new-routing-mark=main passthrough=no
add action=mark-connection chain=prerouting connection-state=new dst-address=\
10.2.40.0/24 in-interface=ether1 new-connection-mark=from-main-to-vrf40
add action=mark-routing chain=prerouting dst-address=10.2.40.0/24 \
new-routing-mark=vrf40
add action=mark-routing chain=prerouting connection-mark=from-main-to-vrf40 \
in-interface=vrf40 new-routing-mark=main passthrough=no
add action=mark-connection chain=prerouting connection-state=new dst-address=\
10.2.50.0/24 in-interface=ether1 new-connection-mark=from-main-to-vrf50
add action=mark-routing chain=prerouting dst-address=10.2.50.0/24 \
new-routing-mark=vrf50
add action=mark-routing chain=prerouting connection-mark=from-main-to-vrf50 \
in-interface=vrf50 new-routing-mark=main passthrough=no
/ip firewall nat
add action=netmap chain=dstnat dst-address=10.2.30.0/24 to-addresses=\
192.168.1.0/24
add action=netmap chain=dstnat dst-address=10.2.40.0/24 to-addresses=\
192.168.1.0/24
add action=netmap chain=dstnat dst-address=10.2.50.0/24 to-addresses=\
192.168.1.0/24
/ip route
add disabled=no dst-address=192.168.1.0/24 gateway=ether2@vrf30
add dst-address=192.168.1.0/24 gateway=ether3@vrf40 routing-table=vrf40
add dst-address=192.168.1.0/24 gateway=ether4@vrf50 routing-table=vrf50
I was able to get this working setup thanks to this post.
Sharing here as a reference for other users.
Any suggestion on how to improve the config is welcome.