Like Crochallan (https://thesession.org/tunes/11647) this tune gives melody to "My Heart’s in the Highlands". It is not only older, but also more complex/sophisticated. And I have highest respect for anyone who could play this one without any flaws and mistakes at the first go.
Failte Do’n Mhisg
I used to play a four-part version of this tune with a band in the 1990s. It can be found in the second volume of The Gesto Collection of Highland Music (1895), where the translation is given as "Hail to Drink". It would be useful to know where your version comes from, aenea15.
T: Failte D’on Mhisg
S: Gesto Collection
Z: Nigel Gatherer
A2 | d3 fed | B4 d2 | A3 dBA | F3 E D2 | E2 F2 d2 | A3 GFE | D2 d2 d>e | d4
d>e | f>efgfe | d3 c B2 | A3 dBA | F3 E F/E/D | E2 F2 d2 | A>BF>AE>F | D2 d2 de | d4 :|
A2 | de f2 f/g/a | f3 e f/e/d | B2 A2 B2 | b3 a f2 | abagfe | fgfedc | B2 e2 e/f/g | e3 d B2 |
dcdefg | a3 b a2 | bagfed | d3 fed | B3 ABd | A2 gfed | B2 ABdF | E4 D2 :|
d2 DDDD | d2 DDDD | G3 dBA | F3 E F/E/D | E2 F2 d2 | A3 GFE | D2 d2 de | d4
fe | d2 DDDD | d2 DEFD | GFGdBA | F3 E D | E2 F2 d2 | (3ABA (3FAF (3EFE | D2 d2 de | d4 :|
A2 | de ffga | f3 e d2 | B2 b2 a2 | b3 a f2 | a2 (3baf (3afe | f2 gfed | B2 e2 e/f/g | e3 d B |
d3 efg | a3 b a2 | (3bag (3agf (3gfe | d3 fed | B4 z2 | A2 gfed | B2 ABdF | E4 D2 :|
Failte Na Miosg
Having just looked up my copy of The Scots Musical Museum (1787-1803) I can see that that is the source of your version.