Is it a sin to read modern Bible versions?  First, you must know that modern Bibles versions are not really modern Bible versions.  Rather, so-called modern Bible versions are really Bible commentaries and Bible commentaries may contain falsehood.

Now, as long as you know that so-called modern Bible versions are really Bible commentaries and that Bible commentaries may contain falsehood, it is not a sin to read so-called modern Bible versions, that is, it is not a sin to read these Bible commentaries.

Remember, only the King James Bible is the Bible.  In addition, in the future, the spelling-updated King James Bible (the International Authorized Version, which contains spelling changes like those that were made in the King James Bible in the past) may replace the current King James Bible.