Well, purchasing 2012 does not put it on your timeline, so I think we need to discard that old trope. I am further proof, as I recently purchased it from Amazon, and had to install it via steam. If N3V doesn't want to be buried in requests for getting these old versions on timelines, they need to fix something in the registration process. I myself have been tempted to put in a request to have 2009, 2012, T:ANE Deluxe Bundle, and TMR added to my timeline, as I have purchased all of them since my original DVD-based purchase of T:ANE std.
Unfortunately, CJman, very few people are doing any development in 2012 at this point. If you want to stay with 2012, I recommend you get what is still available on the DLS and from third parties. Maybe learn to reskin locos yourself. Otherwise, upgrading to a version that people are still developing for might at least get you a reskinner who might be interested in doing your request. T:ANE standard right now is on sale for only $6.99 USD, and will open up a whole new world (T:ANE Platinum for $29.99, TRS19 standard for $39.99, TRS19 Platinum for $49.99)! And yes, it should show on your timeline, since you purchase it from N3V.