B767 First Officer reported a LE SLAT DISAGREE message and a master caution alert on final approach. The flight crew landed and taxied to ramp for parking where damage was discovered on the slats.

Narrative

On the arrival into ZZZ flying Aircraft X. I was pilot flying (PF) and the Captain was pilot monitoring (PM). We had planned for the ILS Runway XXC approach but entering the terminal area we were given clearance for approach for Runway X. We asked for Runway XXC approach but due to outbound traffic off of Runway XYC ZZZ Tower was unable to accommodate the request so we had now set up for Runway X approach. I had the Captain brief the approach as pilot monitoring while I was flying the aircraft. On the downwind I started slowing to Flaps Up clean Speed and called for Flaps 1 and then started slowing to Flaps 1 speed. The Approach Controller then cleared us to descend to 3;500 ft. and the pilot monitoring asked if I would like an extension off of ZZZZZ which is the Final Approach Fix for Runway X into ZZZ. I said yes I would like a Course Fix Intercept off of ZZZZZ for the ILS Runway X. Approach Control then turned us off of downwind on an intercept heading to intercept the Localizer for Runway X and at that point I called for Flaps 5 and started to slow to Flaps 5 speed. Then Approach Controller asked us if we had the runway in sight; at which I did tell the pilot monitoring affirmative I have the runway in sight. We were given clearance for the Visual Approach for Runway X but I still continued to use Localizer and Glide Slope Guidance to fly the approach. Upon intercepting the final approach course just outside of ZZZZZ as glide slope was alive I called for Gear Down and Flaps 20 and at that point the Localizer captured. Not too long after that the Glide Slope captured and I set 3;000 ft. for the Missed Approach altitude in the altitude window and we both pointed and called '3;000' set. I called for Flaps 30 and landing checklist at which point the pilot monitoring set Flaps 30 and I set my Vref Approach Speed plus the wind additive for Flaps 30 and we accomplished the Landing Checklist. Once we passed ZZZZZ and 'ZZZZZ 2400' was called I continued to fly by use of Autopilot and Auto Throttle down to the 'STABLE CALL OUT' at 1000 ft. AFE (Above Field Elevation). It was at that point approaching the Stable Call Out that the EICAS Message 'LE SLAT DISAGREE' appeared and we received the Master Caution Alert. I did call for QRH Non-Normal LE EDGE SLAT DISAGREE checklist but since we were inside of 1;000 ft. and with runway insight the pilot monitoring which was also the Captain decided that we will continue to landing and to increase our Vref speed. At that point I recall that I was flying target at 135 KIAS and increased to 140 KIAS. One final thing that the pilot monitoring did try to do was to change flap setting from 30 to 25 and then back to 30 to see if would reset and remove the message which it did not and we ended up touching down at a faster speed. The winds also on final approach when the flaps were called to be placed flaps 30 after passing ZZZZZ I noticed on my Multifunction Flight Display (MFD) were a direct crosswind from the right at 38 kts. but did start to diminish down to almost 10 kts. at touchdown. Once we touched down the Call Outs of 'Speedbrake UP' and 'Reversers Normal we're made by the Captain and once we slowed to 80 kts.; the Captain took over controls and we made an exit right turn off of Runway X onto X. We were given instructions by Tower to taxi on Taxiway 1 to Spot XX and then contact Company Ramp Control for Ramp entrance. The Captain called for 'Flaps Up' after landing sequence and I performed the necessary steps; but realizing myself that I should've kept the Flaps down since the EICAS Message did not clear. The Flaps retracted and stopped at Flaps 1 and stayed that way. Once we were given clearance to enter Company Ramp and parking; we entered and parked at our assigned parking spot and then performed the necessary steps to shutdown the aircraft. Once complete the Captain called for the Shutdown checklist and that was performed. Once I was given instructions to open the door I went and opened the door and then returned to my seat and we performed the Secure Checklist procedures and secured the aircraft. I then got out of my seat. To check to see if the Ramp Crew had placed the chocks in the correct place in which they did. I notified the Captain that the chocks were in place and he released the parking brake. Once I had gathered my stuff and exited the aircraft to the bottom of the stairs. I performed a thorough walk around post-flight inspection of the aircraft and that's when I noticed that the slats were still out and had not retracted and upon further review noticed that the Right Inboard Slats were both bent beyond the rivets holding them. The Captain had also came out to that area and saw the same thing. The Captain had also wrote in the aircraft maintenance logbook a full right up of the EICAS message. There was no Maintenance Personnel in the vicinity when we arrived but we both explained to the Company Service Representative what had happened and the steps that we performed so that he could pass that along to maintenance. We both left the aircraft and went to the Facility Building and then left separately. Not sure of why we received a LE SLAT DISAGREE Message being that it was close to touchdown and the flaps had been extending normally throughout the approach until that point below 1;000 ft. AFE.Should have not retracted the flaps after exiting the runway and should've left the flaps down in their Flaps 30 position.