Not sure. Here is the etymology of 'hit', according to Wiktionary:
From Middle English hitten (“to hit, strike, make contact with”), from Old English hittan (“to meet with, come upon, fall in with”), probably of North Germanic origin, from Old Norse hitta (“to strike, meet”), from Proto-Germanic hitjaną (“to come upon, find”), from Proto-Indo-European keyd- (“to fall, fall upon”). Cognate with Icelandic hitta (“to meet”), Danish hitte (“to find”), Latin caedō (“fall”), Albanian qit (“to hit, throw, pull out, release”).
It only has this to say about 'buail':
From Old Irish búailid.
Well, Americans do use "bump into" or "run into" when we talk about meeting someone we already know at an unexpected time or place. Example: "You'll never guess who I bumped into at the station;" "How lucky that we ran into each other today." It indicates the meeting was a surprise or coincidence. We wouldn't use it if the meeting had been planned.