FLUX 1 Fill Pro

Experimenting with this model and it tends to insert unwanted objects when I just want it to naturally extend existing context. For example like the two unsightly buildings structures on the sides, or a strange cave exit when it should simply extend the landscape (attached). Varying guidance parameters and prompts doesn't seem to help. Please advise or suggest a different outpainting model. I am giving inputs with diagonal corners or irregular parts of the image missing, which, depending on the image, the model seems to be handling well.