if one valid translation is 'i like the Spring', i would suggest accepting 'i like spring' as well, since it's valid english. If the sentence is more specific than that, i.e. 'i like the season of spring' then 'i like the spring' isn't as correct any more. If the sentence uses tymor as in school term? then this question doesn't at all make that clear.
The Welsh includes the word tymor, which we try to accomodate in the English translation. 'The season of spring' sounds clumsy in English, so we currently stick with:
- I like the spring term/semester/season
If you want to say that you like 'spring':
- Dw i'n hoffi'r gwanwyn - I like (the) spring