How often do Christian missionaries report occurrences of miracles while on the mission field? From time to time I come across testimonies of missionaries reporting extraordinary anecdotes that occurred when they were on the mission field. For instance, I've heard of stories of people getting miraculously healed after getting prayed for, demonic entities showing up at night telling them they won't be able to evangelize in that country, bullets getting deflected, people manifesting as if possessed and getting delivered, etc. The following are some of the most extraordinary anecdotes from missionaries that I've come across so far:
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Question: How common is it that Christian missionaries come back from their mission trips reporting extraordinary anecdotes? How often do missionaries report supernatural experiences of any sort while on the mission field? Do any denominations or Christian organizations keep records of these extraordinary stories from their missionaries?
I have been in touch with individual missionaries, and missionary couples, over many decades. They send reports to prayer supporters and probably even more fulsome reports to any missionary society or church that sends them and helps provide for them.  Some missionaries are self-supporting and do not report back to any organisation or church, only sending news-letters to Christians who pray for them. They are full of miracles “in the field”. I have also read many books about missionary exploits, some in previous centuries. I could not collate any statistics on the frequency of such missionary reports of miraculous events, for there are far too many even with the limited information I have. Nor do I have access to missionary reports outside of Protestant ones although I support Christian Solidarity Worldwide which has a largely Catholic base. When I heard Baroness Cox speak locally, she was asked if she believed in miracles.

“We don’t believe in miracles,” she replied, “We DEPEND on miracles!”

And therein lies the problem with answering your question.
The extent of God-ordained miracles in outreach work of missionaries and those helping the persecuted Church is so vast as to be incalculable. Even if you were to find an organisation logging missionary experiences of miracles from every Christian denomination there is, they would miss out a huge number. There’s a specific reason for that.
It has to do with the safety and protection of Christian missionaries. These days, few countries allow religious missionaries of any religion to enter in for such activity. They can enter in order to fill teaching posts, or do engineering work, or medical work etc, but if they are suspected of also doing Christian missionary work, they will be expelled and never allowed to return. In some countries in the world where, I suspect, the greatest number of miracles are happening, Christians involved (whether missionaries or nationals living there) could end up in prison or even lose their lives. I personally know one man born in such a country who now lives with his family abroad, but visits it (and other countries that are immensely dangerous to operate in), and all his news-letters have miracles in them. Not that he tells us of all such miracles. He would need a book to record them all, and I do not exaggerate. Another couple I personally know go in and out of India, at their own expense, and their news-letters are just the same. They relate some miracles, but many others are only mentioned in verbal exchanges. They, too, would be in some danger if their identities became public.  A family I personally know who spent decades living in Turkey warned every reader of their news-letters not to make the information public.  Another couple I know who were missionaries in Africa happily shared wonderful events with friends in the church but their ‘sending’ organisation who would also know of these events, would only record accounts from missionaries ‘signed up’ to their group.
I doubt if there is any official body collating all records of all missionary ‘miracle’ experiences. And there is no way I would share with you or anybody else the many miracles I have heard of over the decades. I would not even suggest bare statistics because providing those would entail a huge number of hours of searching through those news-letters I kept (from the early 1980s till now), but most were shredded.  This means that your main question is unanswerable (by anybody). Your second question would surely get the answer, “It is not uncommon” from every Christian involved with missionaries. Your third question would require an answer from people in touch with every missionary in the world, and I doubt if even one such person exists. Your fourth question gets a “No such organisation does all of that” from me, but I could be wrong.
This is a less than helpful response to your four questions, but because you ask about a really interesting and important matter, I have risked incurring the wrath of the moderators by posting what amounts to a non-answer, apart, that is, from my answer to your second question - How common is it that Christian missionaries come back from their mission trips reporting extraordinary anecdotes?  -to which I have replied, “It is not uncommon”.