I don't know for sure. But as bun as a prefix usually means the original or the first in a line, and "crot" is probably an older spelling of "cruth", I'd say it means the story as it was originally told/created.

bunchrot = bunchruth (basic shape)
bun- (basic), cruth (shape)

Go raibh maith agaibh. So I imagine it would mean - Being faithful to the original form of the story.
This is what follows -

Theastaíodh ó a lan scéalaithe ó na ceantar éagsula a gcuid scéalta a thabhairt uathu díreach mar ar chualadar féin iad. Léirigh sé seo an meas a bhí acu ar na scéalta agus níil aon dabht ach gur thuig cuid acu go raibh sé de dhualgas orthu oidhreacht a muintire a chaomhnú sa tslí seo:

The teller prides himself in preserving it as an ancient tradition. It is not his but belongs to his people and is much a part of them as any of their customs or beliefs could be.
(quoted from Thompson, Stith, 1938, "Folktale Collecting in Ireland" - Southern Folklore Quarterly 2, 53-8).

Here are some more words for which I can't find the meaning - meudughadh, lughaide.

here's the context -

An tráth do bhí sé curtha anns an uaigh agus seilbh ag an bh-fear óg air rachmus a athar is beag do shaoil an t-ógánach uaibhreach so go d-toicfaidh leis choídhche an t-ór agus an t-airgiod go léir do scapadh, agus budh lughaide do mhachtnaidh sé air a inmhe do mheudughadh.

Old speling:
meud = méad,
-ughadh = ú,
so:
meudughadh = méadú,

lughaide = lúide

Go raibh maith agat, a chara.

Bhidheann - would that be - buíon ? And is - budh - in the past tense or the future ?

Acht is anamh (annamh) bhideann mac gasda (gasta) ag athair coigilteach, agus b'é sin dála na Sgolóige. Tharla do'n sean-duine, air chaitheamh a aimsire dhó, go díthchiollach, saothrach, go bh-fuair sé bás air nós daoineadh an t-saoghail. An tráth ......srl

No, there's a slender bh, and a tense n. This doesn't change, so: bhíonn.
Is annamh a bhíonn ...

Budh is past/condit.

Go raibh maith agat arís.

The big problem I have with this is that the English translation is often quite different from the Irish.

It is seldom, however, that a frugal father has a thrifty son, and that was the case with the farmer. After a long life of hard work the old man died, as happens, and will happen to everyone of the race of men, and as soon as he did the young man got his father's money into his own hands. There was a great lot of it there, both in gold and silver, and it was little the proud foolish fellow thought that he would ever come to the end of it. To increase, or to make safe his nest egg was the last thought in his head.

It's not translated word for word. But most story translations aren't. Some words and idiomatic expressions wouldn't be easily translated into English. It doesn't seem to leave anything important out. At least not in that bit.