"If you need, I would be happy to interpret for you."
- "If you'd like, I can interpret for you two."
"If you'd like" 「よかったら」
"you'd" = "you would"
"I can interpret for you two" 「二人の通訳できます」
- "If you need, I would be happy to interpret for you."
"if you need" 「もし必要だったら」
"I would be happy to~" 「〜できて幸いです」