It's the note length. I don't know what ABC thinks is acceptable, but I used a combination of 3 and 2 instead of 5 for the first tune, and it seemed to work.

T:My Irish Jaunting Car
M:6/8
L:1/8
R:Jig
K:G
DD2DDB,|DG3B2|BAGED2|B,C3C2|B,/2C/2D2DDB,|DG2AB2|
BAFDDE|FG3G2|G/2A/2B2GGA|Bc2BA2|d/2c/2B2GD2|
B,C3C2|B,/2C/2D2DDB,|DG2ABB|Bc2AF2|DG3G2|cB2GGA|
Bc2BA2|d/2c/2B2GDB,|C3C2B,/2C/2|D2DDB,D|G2ABBB|
AFDDEF|G3G2B|B2GGAB|c2BA2d/2c/2|B2GD2B,|C3C2B,/2C/2|
D2DDB,D|G2ABAB|c2AF2D|G4||