This software overwrites original images with modified, so new image must be less or equal (in bytes) to the original.
Try to reduce number of used colors, or image size so image would compress better.
Hmm... I'll try to fix language problems in next version... you may try to switch your system locale to Ukrainian or Russian - that should help.
And about patches - no, you will not loose any patches, because this software will genetate .vkp patches, which contain only modified graphics.
So, I've updated SE db2020 Image Tool.
Now it should work ok on all locales, no more questions instead of letters!
And, a few fixes and new features.