My written Chinese is not nearly as fluent as my speaking, and my dialect uses different slang sometimes, but this would have been a little more clear:
What you sent (past tense?) was understandable, but some of the phrasing and terminology was off.
I used a translation website to write these words. If I have written something wrong, I'm very sorry [about that].
What you wrote previously was only "I used a translate;" a noun like "website" (in red) so that it reads "translating website" is needed to modify the verb. The blue is "to write these sentences," which clarifies the use of the translator. You don't actually need to write "so" (所以), because it's somewhat implied. You wouldn't really use the phrasing "it looks odd" in this way, so it would have been clearer to specifically say, "If I wrote something wrong, I'm very sorry [about that]."
I really like your art (lit. paintings). Keep up the good work!
It's also less common to use the word 愛 for anything but close family and maybe pets; more common is the phrasing for "like (very much/a lot)." 工作 is actually typically used for work as in workplace, and not so much art, so I would have replaced that with the character for painting, 画. The second phrase did translate as "continue [to] work hard," but colloquially, the slang 加油 ("add oil") means much the same thing and is pretty universally used as a way to encourage someone to keep up the good work, much like the Japanese phrase がんばって (ganbatte).