Well you should be able to login with your tiki credential to https://doc.tiki.org/tiki-login.php
From there you can edit pages
Is there any guidance on layout or style for documentation pages ?
May be but it is also may be outdated.
I usually try to find a new created page and stick to the way it was done
I expect to have questions arise as I go.
Forum is great to keep tracking things
Can i18 be a topic for the next meeting
Sure go at : https://tiki.org/Roundtable-Meeting-2018-04
Add the topic
Tiki is a do - do community so go on !