As you can see on the photomap, there are only 3 (in word - three) splitter islands right in the junction. Is there something I do not know that justifies using so long oneways leading in/from the junction? There are no physical central barriers between these oneways, you can easily do a U-turn there.
It’s apparent the author drew them (oneways) along turn lanes or when there are at least 2 lanes in the same direction. Especially on the road coming from the right - the 500m section is 2 lanes towards the junction and 1 lane out.
What do you think?
Is it alright to correct this? I mean - make it a single highway.
Should those two 90° arcs be left in the junction?
Certainly looks like the median to the east, north, and south should be eliminated. My rule of thumb is that, were someone to plop down a driveway to the road, would you be able to turn left to and from it? If so, it’s a single carriageway.
I would leave the two arcs; it’s not clear from the aerial whether there’s a physical barrier, but there’s certainly a separation of right turns, enough so that there are separate crosswalks across them.