It can be solved with a fairly simple macro.
Sub ReplaceTextWithImage(findText as string, imagePath As String)
If Selection.Find.Execute(FindText:=findText, MatchWholeWord:=True, Forward:=True, Wrap:=wdFindContinue) = True Then
Selection.InlineShapes.AddPicture FileName:=imagePath, LinkToFile:=False, SaveWithDocument:=True
End If
End Sub
EDIT: added checking if text found and MatchWholeWord and continue search if out of selection range.
Other checks should be added to the labview code (image file exists and findText not empty).
Note, that the Selection.Find.Execute will ignore MatchWholeWord if there are special characters in the findText for some reason. I haven't found a reference to what charaters are "special". Special characters I tried and found: &, #, _ So I gueass pretty much every non alphabetical....