What's with the delay in ordering rail reservations in Sweden/Denmark/Norway? It's well within my travel dates.
Are you talking about Eurail Pass reservations? I just got to the payment page to get an eticket from Stockholm to Karlstad on April 7. Website is a bit clunky and had use Chrome to get it to work properly.
Never got that far. I was notified that they would let me know when it was OK to make a reservation. Not yet, even though they say that 180 days is the period of availability.
Six months is not a common ticket or reservation availability window; two or three months are more common in Europe.
If you are talking about Eurail pass holder reservations, then Rail Europe has some main lines in Scnadinavia bookable for travel through the end of May. If you need to see which legs require reservation or where the connections are, then the DB link at How to Look Up Train Schedules and Routes Online is an objective resource.