I've never used a Grainfather but I
have made saisons. I love them. You can do just about anything to them and still get a pretty nice beer. So here is my opinion (FWIW): your recipe looks pretty good.
If you want the coriander and hops to stand out the grain bill looks ok. To add a little colour and some caramel/sweeter flavor consider adding some cara or similar. My favorite is honey malt.
I'd ferment way warmer. Safale BE-134 says ideal fermentation is 18-28°C (64.4-82.4°F). Saisons are about the yeast funk which can be obtained better by fermenting warm. I'd start at 18-20 for the pitch and as soon as the fermentation is roaring I'd increase the the temp by a few degrees each day until you get to the 28 or even 29 range then hold it for a week or so, then naturally let the temperature drop to what it wants to in order to stress the yeast and get some of the funk. That said, I've never used BE-134. Your temp plan should give some yeast flavor but if your looking for more bang for your effort I'd go higher.
I'd reduce the hop additions, especially the 60 minute. Try 20 g instead. Your grain bill is pretty light ('L wise) and the hop addition may stand out more than you want. But, some folks (including me) like a hoppy saison sometimes, so ignore this part if you like hoppy.
25 g coriander will be very noticeable, maybe even overwhelming unless you have a stronger malt profile. I usually use about 7 - 10 g lightly cracked in a 6 gallon batch and that is more than enough for me. Very noticeable to my palate. I do like 14 - 20 g of citrus peel added in the last 15 minutes of the boil or dry hopped...but that's just me. You could also add some rose hips or even some heather flower (AKA:Calluna vulgaris) which I think gives a nice compliment to the saison funk. I had a Quebec saison with a floral profile from heather flower and mandarin orange peel and OMG was it good! Unfortunately I forget the name of it.
If your not sure about the citrus or other additions you could take a taste sample when the fermentation is completed and dry hop with any of the spices and herbs you can get.
You don't have a mash temp listed. I'd go for a low mash temp. 148-152 to try for a really fermentable beer which would help with the ABV (saisons should be dry to finish) and the thinner mouth feel. I try for an iced tea kind of mouthfeel in my saisons.
Good luck and enjoy! Saisons are just plain fun. They are such a varied style you really can't really screw them up.