This is issue is not exclusive to the switch, it appears to be an issue with realms in bedrock edition. I am a happy realm owner and have been recently informed of corrupted chunks in the world. The only real way to fix this is by trying to roll back the realm before it appeared. There is no apparent fix or way to prevent this, it seems to happen eventually on realms at some time or another.
Unfortunately due to whatever reason, the portals no longer have an issue, as for the portal coordinates, the one in the nether was naturally generated and has no issues. The portals generated were roughly all in a 7 block radius of the original. I am trying my best to reproduce the bug but it seems that all attempts dont work. It appears to have been resolved but I will try to give updates if I observe the behavior again. No changes were made to the world or the surrounding of the portal