Would have succeeded ??

He would have succeeded.

This sounds like a partial clause extracted from a conditional sentence, such as "If he had tried harder, he would have succeeded." If that is the case, "would have succeeded" is present tense, third conditional, indicating a past event that did not happen.

In a stand-alone sentence expressing a similar meaning, you should write "He should have succeeded." (He was likely to, but did not, succeed.)

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You might not have been late.

This is a present or past tense sentence suggesting a past event with a low possibility. It is impossible to tell the exact tense without more information because "might" can be used in the present tense to suggest politeness, and its meaning is identical to that of "may."
You might be late. (The speaker thinks that there is a chance that you will be late, but you may not be in the end.You might not be late. (You think that you will be late, but the speaker thinks that there is a chance that you will not be.)You might have been late. (You had a chance of being late, but you were not late.)You might not have been late. (You had a chance of not being late, but you were indeed late.)