I don't believe there is such a thing as a "perfect" translation of scripture, but there is an interesting thing to note about the verse you mention. One of the English translations I personally trust the most is the ESV. If you try to look this verse up in an ESV Bible you will find that it skips from verse 3 to 5.
According to their footnote and the Study Bible commentary there is a significant problem with the manuscripts for this passage in that the phrase in question is not found in the earliest known manuscripts. The translators made the following judgement call:
The statement in the ESV footnote about an angel of the Lord stirring the water and the first person who stepped in being healed is found in some early manuscripts, but not the earliest. Therefore the omitted verse 4 should not be considered part of Scripture, although v.7 (which is in all manuscripts) shows that people believed something like what this statement reports.
I do not know much about this particular passage of scripture, but I think it's reasonable to interpret the whole business with the pool to be a folk tradition rather than a valid source of magic healing. I do not know of any recorded evidence of specific/significant/verifiable miracles stemming from the pool, although I don't know that we can rule out the possibility just on principle.
I believe it is important to note that in all cases of healing, the healing stems from God and the focus of our attention should always be on Him rather than whaver medium He chose to use to reveal that healing. One example of this can be seen here:
Matthew 9:20-22 (ESV)
20 And behold, a woman who had suffered from a discharge of blood for twelve years came up behind him and touched the fringe of his garment, 21 for she said to herself, “If I only touch his garment, I will be made well.” 22 Jesus turned, and seeing her he said, “Take heart, daughter; your faith has made you well.” And instantly1 the woman was made well.
I think the important thing to note about this passage is that it was not Jesus garment that provided healing, but Jesus power to heal that He chose to bestow upon the woman on account of her faith in Him (not in His garment).