They showed how the Japanese used patterns in their torpedo attacks and were still successfully surprising the Americans in several small engagements (this was in 1943) in which the Americans were still badly underestimating the effective range of the Type 93s.
The idea that they couldn't hit targets at extended range, or that they couldn't effectively shoot spreads of these based on limited sighting data, or that radar ended their advantages in night combat, or that they didn't still ad up to a major advantage for the IJN even this late in the game is I think, clearly a gross oversimplification.
The argument is not if the Japanese got hits at long range. They did. The argument is wither that made them 2-3 time more effective than the British torpedoes and the British torpedoes were not the same as American torpedoes, even assuming the American torpedoes actually worked.
Yes the British underestimated Japanese torpedo capability. However given the limited amount of interaction between the British and the Japanese the Japanese may have underestimated the British capability. The British may have not sailed in straight lines, fat dumb and happy like the Americans did at times if the British suspected that the Japanese were in torpedo range. (British might estimate range at near 15,000yds like their own or underestimate? The Italian's had a number of torpedoes that could make 13,100yds (12,000 meters) at low speed settings. They had one that could do 50kts at very short range (3-4000meters)
A British surface torpedo (MK IX**) could travel to 15,000yds at slightly higher speed than the American MK 15 did to go 10,000yds. The British torpedo was carrying almost 50% more explosive than the American but a lot less than the Japanese.
Now at "close" range we have these combinations.
Japanese...........................48-50kts..............................21,100yds, which pretty much covers most but not all of the torpedo launches the Japanese did.
British..................................41kts...................................11,000yds
American(H).....................45kts......................................6000yds
American(M)....................33.5kts...............................10,000yds
British are about 83% as fast as the Japanese out to 11,000yds?
I won't debate the point on the air launched torpedoes, as I know the British were of good enough quality, but I would point out that most of the Japanese aircraft capable of delivering torpedoes were much better, in particular had much better range, than the FAA equivalents. The IJN also (arguably) had more effective long range land based aircraft for torpedo strikes, G3M and G4M bombers, though eventually the torpedo carrying Beaufighters would fit very well into this niche for the British.
The Torpedoes themselves show little difference, yes the Japanese had better planes, kind of.
Both countries had problems putting big torpedoes on their aircraft. Big in this case means heavy warheads on 18in (17.7) torpedoes.
The G3Ms used lighter warheads than the G4M and the Kates, but these only had a 452lb warhead.
British carrier torpedo planes used 388lbs warheads (later 432lbs with Torpex)
Late war shore based planes could carry torpedoes with 545lbs of Torpex.
The thing is that while the Long Lance showed a very marked advantage over the Allied torpedoes the same cannot be said for either the aircraft torpedoes or the Submarine torpedoes. The Japanese traded range (understandable) for warhead size with the Submarine oxygen torpedoes.
The Type 95 had a max range of 13,100yds at 45-47kts with a 405kg warhead.
The Type 95 mod 2 had a max range of 8200yds at 45-47kts with a 550kg warhead.
The Type 96 mod 2 had a max range of 4900yds at 48-50kts with a 550kg warhead. This used 38% oxygen to reduce maintenance problems.
As far as the range goes, how far can you see with a periscope? firing torpedoes over your own visual horizon is not a good idea. Also remember than the even most of the big Japanese boats only carried 18 torpedoes. Risky shots after it took weeks to get there wasn't a good idea.