OK, here is the macro I promised:
MACRO: Copy Cells in HTML Table to Excel & Set Sign of Red Numbers [Example]
Please let us know if it meets you needs.
I took a completely different approach than the one you were using.
Instead of trying to ID the negative numbers by using Found Image, I copied the data to Excel, and then tested each cell there for the Red RGB color.
I think this is much more reliable, and probably faster as well.