cut us a bit of slack: allow "tidy" as well as "tidy up"
Both 'tidy' and 'tidy up' are in the database as acceptable answers.
'Later' is more usually nes ymlaen or hwyrach. Wedyn is usually used when saying that you will do something after doing something else first.
Although the University dictionary allows 'later' as a translation so I guess we should add it.
There are many variations in translation if many words between any two languages. Realistically, we can only handle some of the most common variations on a course such as this.
There are comprehensive dictionary and thesaurus resources available on-line or in print.