Deck stain advice/help

I have a few questions regarding a new desk and the stain I applied. We recently had a nice new cedar deck built. I had been planning on using ppg(sikkens) cetol semi-transparent matte cedar as the stain. I prepped the deck by doing a light sand with 80 grit. Swept it off after that and waited for a nice and dry 4 days.

I began staining one morning around 8am, the day called for 30% rain so I was optimistic. I knew I wasn't going to get the whole deck done so I was planning on doing half. About 11am it started to rain. After inspection the next day it seems like the area I stained early was ok, but the area that I did closer to when it started raining will need to be redone, unfortunately.

No my other issue/question. Since I couldn't get it done in one day I had to continue the stain on the rest of the deck. When I applied stain up to the line of where I stopped previously I got some harsh lines. I also have an issue where some of the stain I applied was applied over the previous stain and now it's shiny and looks terrible.

So here is my question, how should I attack the area with the harsh lines and also the areas that are shiny with 2 coats accidentally on it? I understand why some of the areas are now shiny, its because i have a bit of the stain on top of stain which isn't good. So how do i rectify that?

Thanks for any help on this