Try to get the filler out of that join between the sill and the rear arch panel. Filling that in is a giveaway that a less than ideal repair has been done (polite term for a bodge to get it through the next MoT). It would be a pity to let that happen as you have done a good job of it.
I'm amazed at the good condition under the outer arch panel. Last time I saw one that good it lived in California!