There is only one way that Labour in Scotland can regain a credible position. It needs to abandon the 'international solidarity' scam, and support workers power in an independent Scotland. I.e. support a second referendum, actively work for independence and cease to anathematise the SNP. I say this as a former (for 50 years) Labour voter.
My view is based on the actuality that the party in power in Westminster has for many years now not been the majority party voted for in Scotland. Furthermore, every tory government (and some Labour) have put the majority (inevitably English) interests before Scottish interests. There is nothing surprising in that, as the population of England vastly outnumbers the combined populations of all the other nations in the UK. However, this democratic deficit is unjust and unsustainable, and is the driving force behind the SNP.
Labour have to give up on the hope that they will regain power in Westminster with the help of Scottish voters. That ship has sailed. If Labour is to regain power in Westminster it must do it solely through English votes (as is only reasonable - if it can't then that raises the question of why not? The answer to that won't be found in Scotland).