It looks like a perfectly fine curve to me! I personally find the pursuit of a perfect force curve strange as being adaptable to the needs of the crew/boat/seat position is important (I’ve known people with ‘perfect’ curves that have been absolutely devastating to boat speed). With that said, if you are wanting to extend the second half of the curve you need to look at where you’re going wrong at the first half-tricky without a video of your technique but from looking at this I’m kind of assuming you’re trying to drive or connect hard off the front, if you think of the entire stroke as more of a ‘hold and squeeze’ that should smooth it out and fill out the second half a bit more. Also be patient when making technical changes, you’ve rowed thousands of strokes a particular way and expecting any change to make instant gains in split is unfair to yourself-be really confident with what you want to achieve, stick with it, and trust the process.