That's one perspective, and not a biblically-sound one. Another perspective is that God is holy, and that we as his creations (clay to His Potter), we are utterly subject to His will. He loves us and wants "all to be saved". However, because of the sin of Adam, we are unholy, having chosen to rebel against Him. As such He is completely justified in leaving us to the consequence of our sin: death. In His mercy He has made a way for us to escape eternal judgment: through faith in Christ's atoning sacrifice.
When we start with our concepts of goodness, justice, mercy, and all the rest, and compare God to them, we might conclude that He doesn't measure up. When we start with God and compare our concepts to Him, we recognize that it is our concepts that don't measure up.
And I agree... that doesn't depend on the translation of Scripture.
As to our ability to sin "in heaven", I think you're missing the part where our sin nature will be expunged. We won't have the irresistible proclivity to sin anymore.