I never heard of ‘plate’, but if MATLAB will open the .fig files, see if you can get the data from them using the plotyy handle graphics capabilities.
See specifically the sections using the
construction, and the associated documentation.
Use the get function to see if you can recover them, after you open the .fig file and plot it, for example, something like:
h1c = get(gca, 'Children');
Xdc = get(h1c, 'XData');
Ydc = get(h1c, 'YData');
You might be able to get the data from the .fig file figure handles after you open the figure, and then re-plot them. (If you have access to R2014a or earlier versions, it might be advisable to use them to open the files instead, since the earlier handle graphics are a bit more flexible and easier to work with.)
No promises — I have no idea how ‘plate’ structures its .fig files.