See supplied patch with id 17234.
__Whitespace__
1. When exporting to XLSX the comments suffix included a blank between the culture name and "[Comments]"
2. When importing from XLSX the code expected no blank if the default (empty) culture was being processed
I've moved the suffix to a const and use it in both places
__Column indexes__
I use the data gathered during `ReadCultures` to calculate the range of cells to read
```
var commentColumnIndexes = cultures.Select(x => x.CommentColumnIndex);
var textColumnIndexes = cultures.Select(x => x.TextColumnIndex);
int lastColumn = commentColumnIndexes.Concat(textColumnIndexes).Max(x => x);
```
__Whitespace__
1. When exporting to XLSX the comments suffix included a blank between the culture name and "[Comments]"
2. When importing from XLSX the code expected no blank if the default (empty) culture was being processed
I've moved the suffix to a const and use it in both places
__Column indexes__
I use the data gathered during `ReadCultures` to calculate the range of cells to read
```
var commentColumnIndexes = cultures.Select(x => x.CommentColumnIndex);
var textColumnIndexes = cultures.Select(x => x.TextColumnIndex);
int lastColumn = commentColumnIndexes.Concat(textColumnIndexes).Max(x => x);
```