Answer
A User Task and a Termination/Failure End Event genuinely can't coexist in the same workflow — that combination is rejected outright, so a single workflow can't natively show both a success-confirmation form and a distinct end-event failure message; the practical alternative pattern is building custom error messaging into the flow itself (via a custom action call) rather than relying on the termination end event's own messaging. Separately, an API task's "Log Errors" option lets a lookup/read step that would otherwise hard-fail (like a Resource Not Found on a missing record) log the error and continue the flow instead, so the workflow doesn't need extra branching just to tolerate a missing record on a read step.