What admissibility means
Admissibility is the threshold question a court asks before it will even look at your evidence: is this the kind of thing the rules allow the judge to consider? Something can be true and still be kept out because of how it was gathered or presented, and something can be admitted and then given very little weight. The two questions are separate.
For a co-parent keeping records, admissibility is why form matters as much as substance. Courts tend to trust records that are relevant to the issue, authentic (clearly what they claim to be), and kept in a way that shows they were not edited after the fact. A pile of undated screenshots is weaker than the same events logged the day they happened with times and context intact.
Example: two parents both describe a missed exchange. One has a note typed from memory weeks later; the other has a dated entry made that evening plus a timestamped photo of the empty meeting spot. Both may be relevant, but the second is far easier to authenticate and harder to dismiss.
The specific rules are technical and differ by state and by court, so whether any particular record comes in is a question for your attorney. Your job is to keep records clean enough to give them the best chance.