Is it possible to add feature for change nickname(with prefixes and suffixes from ColoredTags) transparency in the tablist, when player go AFK?
Transparency, like when you set 3-rd GameMode. As in this screenshot - http://prntscr.com/9rync1

I don't think this is possible with Bukkit APIs. It probably requires packet manipulation with NMS/OBC/ProtocolLib.

Sadly, transparency would have to be hacked via packets, which may cause issues considering the way this is done is by telling all online players that player x is in spectator mode. Changing the colour name of the player when they're AFK is easy but it could cause issues with other enabled plugins.

This feature has been implemented in build 263.