My question involves landlord-tenant law in the State of: Washington

I am uncertain how to interpret RCW 59.18.190, which states, "Whenever the landlord learns of a breach of RCW 59.18.130 or has accepted performance by the tenant which is at variance with the terms of the rental agreement or rules enforceable after the commencement of the tenancy, he or she may immediately give notice to the tenant to remedy the nonconformance. Said notice shall expire after sixty days unless the landlord pursues any remedy under this chapter" and I would like some help with this.

I will also provide some context in case someone may redirect my attention to something more applicable.

In September 2018, I was given notice that renter's insurance would be required starting in November. Then, and now, I am no longer in a lease and am in a month-to-month agreement; Nevertheless, it seemed pretty clear the addendum included in the notice applied regardless of my having a current lease. The notice said the addendum would apply whether I signed and returned it or not. I never returned it because it didn't seem necessary. I pursued getting renter's insurance, but life got in the way, and I eventually forgot to finalize it. 9 months went by and I never heard anything from my property management about it. Then, on April 23, 2019, I received a noticed that I had been charged for three months penalty and would have three days to respond (i.e. show proof of renter's insurance) or be charged again for May. I do not dispute the penalty fees charged up to April, despite the fact that it seem inethical that they could charge me fees with no warning prior or during that time. However, because of life, I knew I could not respond within the three day window. I had concerts that week and a job interview in another city. I wrote to the leasing manager by email asking for a week rather than three days and they refused. (They also refused to speak with me by phone and insisted on all communication by email). So, I couldn't get the renter's insurance until May 2, but I submitted it then by fax and included a letter, again stating that I would pay the penalties I owed prior to the notice, but that I did not think it was fair to charge me another month's penalty with such short time to respond. The leasing manager feels I have been given "sufficient" notice since I was notified of the addendum in September.

In the meantime, I have paid my rent on time for every month between September and now, and it has been accepted by office. So I guess I have a few related questions: (1) Does RCW 59.18.190 provide any indication that the landlord has acquiesced since it has been beyond 60-days since they noticed my error (indicated by the fact that they have apparently been charging me for three months without my knowledge) and since they accepted my rent for this long without any attempt to collect the debt until 3 months into it? (2) Can they really only give 3-days notice before charging another non-refundable fee? and (3) Is no communication between Sept-April about this issue really sufficient?

Thank you so much for any suggestions or knowledge out there!