If you left the front derailleur high enough to clear the 52T big ring then, yes, that will make shifting to (and from) the replacement 47T ring worse. The general rule is that the outer cage plate of the front derailleur should clear the big chainring's teeth by only about 2-3 mm. You shouldn't need a new fd but should reposition your current one.
The other problem is that newer chainrings have ramps, pins and shaped teeth to improve shifting and these enhancements are position-specific, that is the outer chainring will have different shifting aids than a middle chainring. When you put a former middle ring on the outside, you lost the specific aids and they may, indeed, work against good shifting. I don't know the vintage of your Stronglight crank but if it has enhanced chainrings, that could easily contribute to your problem.
Finally, chainrings made for outer position use often have a pin projecting to the outside to keep a spilled chain from jamming between it and the crank arm. If you use a middle position ring, you won't have that protection unless your crank arm has the pin built into it.