Default to the temporary directory when regular directories are read-only

Preferences=>Storage has a couple of folders, but if they're read-only then it prompts error messages.

Will you consider using the temporary directory instead in such cases?
There could be an option of "fall back to the temporary directory in case of an error".

Sorry, I'm not sure what you mean. WinSCP default to the temporary folder for storing the temporary files, unless you override the defaults.