I’m not familiar with the program you’re using.
Is the second screen shot your finishing water profile AFTER your additions? If so you’re pretty close. I personally would target closer to 5.4pH.
I personally feel your belief of lactic acid is totally unfounded. I’ve personally only used lactic acid and have never had a reported issue. Studies out there indicate that it too is unfounded and takes quite a bit of lactic acid to affect flavor. Of course, this is taster specific like any other off flavor. And with that grain bill you’ll need to use far less than phosphoric acid to reach your desired pH.
Chalk is pretty much undissolved in water. You have to use CO2 to get it to dissolve. You can use a bottle and carbonater cap. It’s easier to just skip chalk additions.
1) using volume measurements are really unreliable. You get more accuracy by weight.
2) I would avoid using any city water profile. Although that might be the “reported historic” water profile you are unable to know if the water was treated. Or that water could come from an insight we’ll. I’ve had much better success shooting for a water profile based on SRM.