You could make a ValidationMessage-variable (string) and build that in sequence where required and display that in your pop up. So it effectively is 1 message but it's contents are variable.
That's one way to do it. Assuming you want it in a popup.
Does the validation happen on database level, on the front-end or in a microflow that is being triggered? The different ways and places to validate may give you different options for what you require.
I assume the error shown comes from the validations you set on the entity. For user friendliness its better to catch these validations in a micro/nanoflow before the system does it on commit.
You can compose a validation message in a microflow like Damien suggests or you can put your validations in the right order in the microflow and do a show validation feedback for each error you run into.
try you can try extracting the number from the string using regex and then sort the list according to your requirement . This will help you to get the desired result.
You can use the below links for regex.