Here is the new Atlanta-Pacific route yet to be created for Train Sim World 2. It would go from Colon to Balboa. The route is over 47.6 miles. It would be set in the present day. The rolling stock would include GP10's, F40PH's, SD40-2's, and SD60's with freight and passenger equipment.
So can you detail what steam locos or excursions use the line? Although I have heard of it, sadly probably a little too obscure for a commercial project not to mention the challenges of researching it.
1 problem with the Panama Canal Railway is its partially owned by the Kansas City Southern, which is a US Class 1 railroad that DTG currently doesn't have the license for. Which is also further complicated with the ongoing KCS-CP merger. So untill that is ever solved, dont expect this line to come to TSW2 anytime soon (Or at all) Though it would be fun to see F40's pull Gunderson Twin Stacks.