lipu tenpo is currently not specifically based in any one country. This makes this very complicated.
For safe measure, go with an expiration date of the author's death + 70 years. If an author died in 1960, you can translate their work and so on from the year 2030. Being given explicit permission from the author will also suffice.
Every article submitted is under CC-BY-SA 4.0 - the licence being owned by you, not by lipu tenpo. This licence is irrevokable; once you submit your article, it is now bound under CC-BY-SA 4.0 until the copyright expires. Read more about it here: https://creativecommons.org/licenses/by-sa/4.0/
If you do not agree with CC-BY-SA 4.0, but would still like to submit, feel free to discuss this with us! Contact information is in the description of the form.
By submitting work that has copyright active on it, that does not belong to you, and you do not have permission to use, you are putting lipu tenpo at risk of a DMCA notice, which would result in your article being taken down, and a lot of work for us.