Hello Tvoltage!
Wonderful questions and I do commend you for asking them and of course I commend you as well for getting back into emoticons!!
" Would anyone know if we're still able to submit emoticons to Deviantart to be used in the "add media" tab?"
Yes!! Most definitely you can have your submitted emoticons used in the "add media" tab. How? Read on!!
First of all, as you know DA uses hashtags to help deviants correctly identify and also find artworks easily. Once you are submitting your artwork to DA ensure you are using appropriate hashtags that describe your work and the category.
For example: I submit an emoticon to DA and I use hashtags suchas #emote, #emoji, #emoticons, #smiley, #pixelart, [these are some ideas as to what category of art your design is] then you can use hashtags describing the design such as: #woe, #green #upset, #omg, #handsup, #noes so on and so forth. I was able to find this emote simply by using the "Add emoticon or Avatar tab", clicked on "Community" clicked the magnifying glass and then I typed in #looking which is one of the hashtags you assigned and I found your emote!! So it's quite possible to find it.
Also, for the emotes I posted after Eclipse, I did double check and make sure they were tagged properly as #emote, #emoji, #emoticons, #smiley, #pixelart. Still, these emotes seem to be unsearchable in the "add media" and "add emoticon or avatar" tab. They ARE searchable with DeviantArt's main search bar though, so it's not like the tags aren't functioning.
(Thank you again!)