I was told by support that the player had advanced far enough on the continental map that they were receiving the higher age troops (unattached) through certain events, quests and rewards given during GE.
troops out of age thru GE not possible troops awarded thru GE will match your town hall as far as the reward chest are involved as far as per relics they will match your current age if you age up mid way thru a GE the chest rewards will match the age you were in when you started but the relics will match the age you are in regardless when the GE was started
getting troops out of age can be obtained by simply doing the story mission not a huge secret
get far enough and you will get certain quest that will offer them as either set rewards or as "hidden" rewards usually a player must traverse the continental map and acquire certain sectors or provinces and push as far as they can support the progress. There are quest that create "Tech Blocks" to prevent further advancement in getting these type of rewards a example i am in PE i have gone far enough in the main story quest that i am unable to continue to gather more unattached troops beyond my age due the requirement of the main story quest which is for research of two tech of at the end of that age before the main story quest will continue again
here are some visual aids
this first one is the picture of the main story quest and above it shows my current age (above the forge point bar)
those two techs needed to continue are at the end of the PME Tech tree
At this point i am halted from going any further and gaining troops well beyond my age
i will have to research the rest of Progressive , Modern , and Post Modern before i can continue to gain any progress on this again i am "Tech Blocked " at this time
i have managed to gather troops from Modern and Post Modern like many others have done this its not that hard to solve how to get troops ahead of age if you can manage to gather all the goods you need to get thru the sectors its possible just keep in mind if you choose to do those Events which sometimes yield good prizes it might be difficult to complete. We have now recently seen a alternative to the scout requirement and even the research a tech but they have yet to do a alternative to the conquer a province
sorry this is a long winded post but i hope this helps with some answers