I like that you used this specific example, because that is used a lot when I say I don't like Fail Forward.
I don't see this specific example as "failing forward", because if the player's objective was to reach that city, it is for some reason, usually bound to the plot (find a mcguffin, consult a sage, get a ship, etc). By making the failure equal to them NOT reaching the city, you basically failed the adventure. The fact that you used the hook to start a new adventure (getting lost into the goblin-spider forest) don't mean they continued with the adventure they wanted.
On the other hand, making the failure being something that just expend extra resources (time, consumables, surges, etc), then the check is no longer interesting. Is as interesting as rolling to avoid being smashed by the giant boulder: You want success, but had no control on why you have to make the roll in the first place.
So, to me, when my plot demand the players to reach a city because they need to reach that city, I just skip to them finding the city. If there is a time limit and I want to add tension or drama, I don't link it to a SC with the Fail Forward motto. I put an encounter with some mercenaries hired to delay them. I give the villains access to a linked portal that allow them to arrive first.
I take some hints from Julio Scoundrél. But I make them reach that city just because failing to do so means the story is over.
If the concept works for you, congratulations. I hope you make good use of it, and that it make great games on your table. It just never "clicked" on me as something good, but on the other hand, I also don't like Call of Duty and some people do. Different people, different types of fun, I guess.