Is it okay for hard pen calligraphy to be empty and symmetrical?

Of course. When creating calligraphy works, some space must be reserved, which is called blank space in calligraphy. The purpose of this is to make the work look less full. The space left above is called the sky, the space left below is called the ground, and there should be a space at the end of the work, ready for signature and seal. This is the unified requirement and standard of calligraphy works.