Shouldn’t different bible versions and commentaries be synced and just a flick away? By flicking the screen right or left to move to the next screen you would have instant access to your alternate bible versions and/or commentaries.

In 4.0, they are.  Sort of.

The new "volume scroller" should accomplish this.  If you tap in the lower right corner, then drag up, you can select any "volume".  (A volume is a Bible translation, commentary, dictionary, or other book.)

Bibles and commentaries should be "synced" I believe, so if you're reading John 1:1 in the KJV, and bring up a commentary, you should be in the same place.

Of course, "Analyze Verse" does this in an even better, more consolidated way, only using a single verse at a time.  Just tap the verse number and tap "Analyze Verse."

Just as an aside -- no, analyze verse is not buggy when it comes to commentaries.  It works the way it's designed.  What am I talking about?  Every time you use "Analyze Verse" you may get a different list of commentaries to choose from, and at first it can be confusing.  What's going on is this:  Analyze Verse only displays commentaries that have an entry for the current verse.

So, for example, Genesis 1:1 may have an entry for all 5 commentaries you have installed.  (Every commentator has an entry for Genesis 1:1!)  But move to Genesis 1:2, and only 2 commentaries may show up.  The other 3 commentaries may have no entry for Genesis 1:2.