5e doesn't handle 4e-style 'set piece' encounters very well (they tend to be too complex for TotM, and the numbers of enemies present can drive difficulties pretty high, and there won't be enough of them because 5e assume more/smaller/easier/faster encounters both per session and per day), and 5e lacks any sort of skill challenge mechanics, so a 4e adventure is not going to convert smoothly.
You might use one as a general source of inspiration, though. Read through the 'story' portions and see if it sparks any ideas, then design your own adventure using 5e guidelines and stats. Or, you can keep the situations and creatures (just using 5e stats where available, don't try any sort of numeric conversion formula) as a starting point, not worry about 'balanced encounters' at all, and run as more of a sandbox - if the players bite off more than they can chew, it's on them. If they come up with ways to 'divide & conquer' the larger encounters and take on fewer enemies at a time, they'll do fine.