Eventually means if you wait long enough, i.e., for some unknown time. This conflicts with the successive event, which will happen at some fixed time later. One of the following:
[1a] ... it will eventually fail to detect successive events.
[1b] ... it will fail to detect the successive event
1a, if you don't know which event will trigger the second failure; 1b, if you know it's the very next one. Note that the issue is not a grammatical one, but rather one of semantics.
The choice of tense is a matter of style:
[2a] If the XXX device fails to detect a YYY event, then XXX will fail to detect successive YYY events.
[2b] If the XXX device fails to detect a YYY event, then XXX fails to detect successive YYY events.
2a is a natural way to phrase a simple present narrative, as though you start the test in the conditional clause, and look forward to the future for what happens in the conclusion. 2b, on the other hand, uses the historical present for both clauses. In this case, all the testing has been done, and you are reporting the ongoing truth of the test results. This issue is also not a grammatical one, but one of style.
In a cycle and during a cycle are synonymous.