Repair external corner in plastered interior wall

[Lucky89]

Bought an apartment and tore down the interior wall towards the kitchen to open it up. The wall looks like it's made of leca/light concrete(?) that is plastered. Now to my dilemma on how the heck I should fix this so that it becomes even, nice, and durable? Is it enough to build up layers with something like gypsum plaster and use some corner protection? Considering framing up on the right side towards the kitchen and the ceiling for support, but it doesn't work on the other side because the wall needs to be smooth towards the kitchen and I prefer not to tear down more to avoid making it worse. Any good tips??

 

[Anonymiserad 405730]

Bought an apartment and torn down the interior wall towards the kitchen to open it up. The wall appears to be leca/lightweight concrete(?) that is plastered. Now to my dilemma about how the heck I should fix this to make it even, nice, and durable? Is it enough to build up layers with something like gypsum plaster and use some corner protection? I'm considering framing on the right side towards the kitchen and towards the ceiling as support, but it doesn't work on the other side because the wall must be smooth towards the kitchen and I prefer not to tear down more for fear of making everything worse. Any good tips??

The best mortar for lightweight concrete is Finjas Laga vägg since you can build thick layers and it's more durable than gypsum plaster, which is quite soft in outer corners.