Certified translation of chats and emails?

[MarceloDonaldo]

I'm applying for a PBS dependant Spouse Visa and I am confused with the evidence to support and show that I have had a relationship for more than 5 years, and just recently married. Does anyone know if:
1. Do I need to certified-translate evidence of continuous relationship like email screenshots, whatsapp scripts or chat logs? What if we are always using memes and links?
2. Photo albums and invitations should be explained or dated on paper?
3. What barcode should present this evidence? "Other documents", "proof of relationship" or "Appendix II"?

I also don't want to overwhelm the officer with irrelevant evidence, but I am having trouble differentiating how important can some letters be:
4. If I will be sponsored as a dependant, and the application is taking the CoS number from the main applicant, should I still present some invitation letter from the sponsor or the main applicant? Or a letter that states they will cover for me financially? OR should I just trust the CoS number?
5. We have lived together for years, but in several different houses and with other relatives, sharing rent and no contract or lease mentions our names. Is a copy of contract + a shared rent verification letter from the one in the contract enough to prove cohabitation?

Thanks for your help.

[MarceloDonaldo]

Through reading some testimonies on internet I found out it doesn't hurt to present a letter from the sponsor confirming they will support the main applicant and me for a month. Similarly explaining my personal circumstances through documents and letters with witnesses and utility bills.

Now I mainly wish for some advice over:
1. Do I need to certified-translate electronic evidence of continuous relationship like email screenshots, whatsapp scripts or chat logs if they are in other language different than english?
3. Evidence from electronic records should go under "Other documents" or "Appendix II" when I submit my papers in the application center?