Use of "would" to depict uncertain future
"The trial would" isn't appropriate because the trial is definitely occurring. "The trial is estimated to enroll 50 participants." sounds reasonable. Other options that you might consider or find useful are:
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The trial is currently scheduled to enroll 50 participants.
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The trial aims to enroll 50 participants.
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The expected enrollment in the trial is 50 participants.
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We anticipate a trial enrollment of 50 participants.
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A trial enrollment of 50 participants is planned.
These are all essentially equivalent.