In a text on the Articles main tab, click where you want, and then look at the marker on the left side of the WYSIWYG pane. Its color shows the type of line:

•Black triangle: the line is justified within specified settings of word and letter spacing.

•Brown triangle: loose line, i.e. a justified line containing word or character spaces that exceed the maximum word space values in the hyphenation and justification settings.

•Orange triangle: tight line, i.e. a justified line containing word or character spaces that exceed the minimum word space values.

To check other lines, just press Down Arrow or Up Arrow key to move the I-beam.

Explanation

Because composing a line of type involves many factors, it is not always possible to justify it according your settings for word spacing and letter spacing - some lines may be loose or tight.

Such compositional problems can be reviewed only in the WYSIWYG pane of the Articles main tab.

You have to check line-by-line, manually.