Wasn't looking to do it, but I did a little research into this. The problem is that the game doesn't remember all the trigger information that you enter into such an event. The game will remember Territory Variable 2 for example, but doesn't retain the information about WHICH territory the event was setup to apply to.
An event to Set any of the Territory Variable 2 values to 10 temporarily, will on the conclusion set all Terrritory Variable 2 values to 0 (tested in 1.05). No territory is safe.
An event to Add 10 to Territory Variable 2 value temporarily (+10), will upon rewind Subtract 10 from ALL Territory Variable 2 values (-10). The original event will be "unwound", but all other Territory Variable 2 values end up -10.
Any effects that apply to specific territories and some of those that apply to companies are the same. If I try to temporarily increase Lumber production by +10% in one territory, upon un-wind production there will return to normal, but elsewhere will be down by 10%. If I temporarily increase stock prices by 50% for the player's company, upon un-wind my stock prices return to normal, but all other companies are down -50%.
The problem is the "automatic" event that RT3 automatically creates to unwind each effect. These are called "Temp offset for {EVENT NAME}". If you look at these you will find that they LOSE the trigger conditions that we specified in the original event. Consequently the un-wind effects will be applied to ALL Territories (specific territory), the WHOLE GAME (specific company/ies), or ALL Players (specific Player, variables only?).
I did find that some Company specific effects were un-winding correctly, bridge building and track maintenance cost worked, overall track cost and stock prices did not. The Temp. events look the same for all.
![Confused :-?](./images/smilies/icon_confused.gif)
More investigation is in order, and maybe eventually a list of what works and what does not for companies. Maybe that's why this issue hasn't been talked about much before.
On the bright side, maybe it can occasionally be subverted to get an all-but-this effect.
![Idea :idea:](./images/smilies/icon_idea.gif)
Also, thought it was important to add that temporary events work as advertised if they are used game-wide or if you only need to use one of the variables as Ned did in New France: when he only used the Player Variable 3 for the human player and ignored those for the 2 AI players.
![thumbs_up !*th_up*!](./images/smilies/ok.gif)