Hi Joshua,
Currently it is not possible to find & replace text in a “Text/Comment” object unless the labels were added to the label library:
Example: The “Add to Label Library” button is shown below.
Once a label is added to the label library it can be used in other objects by selecting the “Use label library” check box within the label tab:

When objects within the project reference labels from the “Label Library” the text can be modified through the following process:
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Select the “Project” tab and click “Label”:
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Modify the text within the corresponding language:
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All objects that reference this label will reflect this change.