Yes, this subtest is usually given. It's scored on fairly specific criteria, which differ from item to item. Unless called out in scoring, spelling and punctuation may or may not count against the score (there are other subtests for that). My main issue with the subtest (on both the III and IV) is that it doesn't include any extended writing. So it tells you something about the student's sentence-level writing skills, but very little about the capacity to generate and organize lengthier text, which is a distinction that becomes increasingly important as students progress through the grades.
Overall, the WJIV can be quite helpful in Dx-ing dyslexia, depending partially on just which tests are given. It's based on a selective testing model, where the examiner is supposed to make decisions about further testing after giving the core subtests. In addition, there are three main batteries (cognitive, oral language, achievement), which contribute distinct and overlapping data.
If I were looking for indicators regarding dyslexia, I would start from the reading and phonological processing tests, and then expand from there, depending on the findings.
Could I email the results to you because I'm really having a hard time making sense of them. The report was printing up that day and the format of it is confusing me. I will be getting a more detailed report in a few weeks but in the meantime I'm still trying to get what she needs in school and need to know if there is anything in her tests results that should be brought to the teacher's and/or school's attention.