Lets go back a little bit in time. In the times when the OpenWrt and LEDE fork happened on april-may 2016, I don't remember the exact date, in that time, after the fork, both projects seem to have working in different repos and accepting pull request for devices in each project independently. The Linksys E2100L pull request and support got accepted in the OpenWrt project on Nov-30-2016 and snapshots were generated in that time trunk bleeding edge, in that time we could download snapshot images for the E2100L in the OpenWrt project page
Then the merge of both projects happen, and merged the majority of supported devices, one of the devices that could not see support in LEDE was the E2100L, for some reason this device was not merged in LEDE, and in current Openwrt trunk builds, there is no support for this device.
Now that we came back to the present from our time travel, and that the both projects seems to be joining in one (OpenWrt) again, I think that can be cool that this device could be official supported again in OpenWrt.