I am testing this,..and seems to be working fine with below:-
Juniper to Cisco VLAN swap
Juniper side
set interfaces ge-0/0/6 mtu 9216
set interfaces ge-0/0/6 unit 0 family ethernet-switching port-mode access
set interfaces ge-0/0/6 unit 0 family ethernet-switching filter input no-cos-bpdublock
set interfaces ge-0/0/6 unit 0 family ethernet-switching filter output bpdufilter
set vlans VLAN_920 interface ge-0/0/6.0 mapping 3322 swap
set vlans VLAN_811 interface ge-0/0/6.0 mapping 3321 swap
set vlans VLAN_199 interface ge-0/0/6.0 mapping 3326 swap
set vlans VLAN_921 interface ge-0/0/6.0 mapping 3325 swap
set vlans VLAN_821 interface ge-0/0/6.0 mapping 3323 swap
set vlans VLAN_920 vlan-id 920
set vlans VLAN_920 dot1q-tunneling
set vlans VLAN_811 vlan-id 811
set vlans VLAN_811 dot1q-tunneling
set vlans VLAN_199 vlan-id 199
set vlans VLAN_199 dot1q-tunneling
set vlans VLAN_921 vlan-id 921
set vlans VLAN_921 dot1q-tunneling
set vlans VLAN_821 vlan-id 821
set vlans VLAN_821 dot1q-tunneling
Cisco side-
interface GigabitEthernet1/0/6
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 3321-3323,3325,3326
switchport mode trunk
spanning-tree bpdufilter enable