Yes, the language matters and the court will dismiss your eviction case on procedural grounds–no matter how deserving on the merits–if the language is wrong.
Some documents, such as the 14-day notice, must be in the exact verbiage required by statute. In some local jurisdictions, such as Federal Way and Seattle, additional specific language must be in the notice. Most other eviction documents, while the exact language is not mandated, must have certain types of information.
Some eviction documents were changed in 2019, and then changed again in 2020. Local laws changed in both 2019 and in 2020 requiring additional specific language.
We see some multi-state websites that show up in Google results with form generators that create notice forms that will not hold up in Washington courts.
Be sure to use forms created by a local landlord-tenant attorney. The eviction forms on this website were created by a Washington landlord-tenant attorney practicing in King, Pierce, Snohomish, and Thurston counties and are up-to-date.