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Things are very different now.
The Internet allows people to learn about languages and meet other language
enthusiasts from all over the world.
Instead of working on their projects in private, they can easily find other like-minded people to share their passion,
celebrate their achievements, and encourage each other along the way.
They could even work together on language projects that Tolkien may have never been able to imagine.

Instead of working on their projects in private, they can easily find
other like-minded people to share their passion, celebrate
their achievements, and encourage each other along the way.
Instead of working on their projects in private는 Instead of가 이끄는 전치사구이다.
share their passion, celebrate their achievements와 encourage each other along the way는 콤마와 and로 연결되어 병렬 구조를 이루며 to에 이어진다.
They could even work together on language projects that Tolkien may have never been able to imagine.
that Tolkien ... imagine은 language projects를 수식하는 관계절이다.
may have been은 「조동사+have+과거분사」 구문으로 과거에 대한 불확실한 추측을 나타낸다.