There is no NAT related config on ACE, so I believe that load balance is not using source translation.
On the backbone, there is route-map configured on the Server vlan. This route-map is used for "set IP next-hop", but I cannot understand the purpose of this route-map. Can you explain? The config below is part of actual config but modified.
### ACE ###
probe tcp 8000
port 8000
interval 2
faildetect 2
passdetect interval 5
passdetect count 5
rserver host ABC
ip address 10.10.10.51
inservice
rserver host CBA
ip address 10.10.10.52
inservice
serverfarm host ABCDE-8000
probe 8000
rserver ABC
inservice
rserver CBA
inservice
sticky ip-netmask 255.255.255.255 address source ABCDE-8000
timeout 10
timeout activeconns
replicate sticky
serverfarm ABCDE-8000
class-map match-any ABCDE-8000-VIP
2 match virtual-address 10.10.1.100 tcp eq 8000
policy-map multi-match ABCDE-8000-POLICY
class ABCDE-8000-VIP
loadbalance vip inservice
loadbalance policy ABCDE-8000-Sfarm
loadbalance vip icmp-reply active
interface vlan 70
description ### ACE-OUTESIDE ###
ip address 10.10.1.3 255.255.255.0
alias 10.10.1.1 255.255.255.0
peer ip address 10.10.1.2 255.255.255.0
no normalization
no icmp-guard
service-policy input ABCDE-8000-POLICY
no shutdown
ip route 0.0.0.0 0.0.0.0 10.10.1.30
### show conn ###
903749 1 in TCP 70 10.75.50.57:52980 10.10.1.100:8000 ESTAB
984007 1 out TCP 70 10.10.1.100:8000 10.75.50.57:52980 ESTAB
### Switch ###
interface Vlan100
description ### ABCDE ###
ip address 10.10.10.28 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip accounting output-packets
ip policy route-map PBR
standby 100 ip 10.10.10.30
standby 100 priority 110
standby 100 preempt delay minimum 150 reload 180
!
route-map PBR permit 5
match ip address ACE
!
route-map PBR permit 10
match ip address ACL101
set ip next-hop 10.10.1.1
!
route-map PBR permit 20