That depends on your definition of "tricky". If you mean something that requires human intelligence, I would say it's the complete opposite. More or less the first thing pilots start doing during an emergency is to follow lists, it's all very procedural and
most failures have been predicted in advance, as well as what would need to be done to resolve them, or at least eliminate the immediate threat -- and if these procedures do not help, you are in a very bad place anyway. There are exceptions, of course.[1] I would say that the "tricky parts", as always, are very generally the situations that we did not predict and did not program for.
[1]: https://www.youtube.com/watch?v=099cHWSbAL8