I think most of the traits you want are plausible for a hominid species, either due to a presence in closely related species or because we can associate them with a (stem cell based?) ability for continuous re-growth.
Given that some of the traits you envision, make them more comparable to great apes than hominids, I think something like that (or maybe a common ancestor) might be a better origin species for natural evolution than hominids.
As for comments on specific points:
Can range in height from 143.2cm (4ft 8in) to 228.6cm (7ft 6in) tall
This range seems a bit much to me if we assume that it all applies to fully grown adults (body plans need to be very tightly controlled, so size variation is usually not very big). It would probably make more sense that your trolls never stop growing, even after they exit the growth spurt of juveniles. Such continuous growth could be caused by increased basal levels of developmental programs / stem cells (which can also explain some other traits you want).
Are mostly covered in a thick, coarse hair. Like that of wolverines
I imagine this similar to a gorilla / great-ape, so most the genes are probably already/still there.
Have an average have a life span of 150-170 years (barring major
A bit higher than other mammals of that size, but given that the trolls seem to have increased health/regeneration this seems fine.
Can fully regrow missing limbs in approximately 1025-1095 days.
This is a tricky bit, because mammals usually don't regenerate tissue. However, it's definitely possible and - like the continuous growth - could be explained by a basal level of developmental/growth programs, which would also explain why it takes so long (even if those programs get more prominent when a full limb needs to be re-grown).
They are not significantly prone to major disease
Like the other answer already mentioned this is not very well defined - diseases come in terms of pathogens but also issues of the own body. For the latter limb/organ/... regeneration abilities would help a lot (i.e. the heart could over time recover from a stroke), while the immune system is of course needed against everything else.
Have large noses, as well as cow-like ears
Noses should be fine, the ears are more tricky (the other answer also mentioned that), as most hominids or even apes/monkeys have quite human like ears.
Their diet consists primarily of plant matter, though they scrounge a certain amount of protein from insects and carrion and will rarely scavenge dead animals
This seems similar to the diet of great apes, so it should be sufficient for an hominid of that size. However, northern Scotland will not provide nearly as much food as a jungle. It may be an explanation for their solitude life style though - they need big areas to find enough food.
Have very sensitive eyes and are nocturnal
One often comes with the other and shifts to or from nocturnal life styles have happened quite a few times during evolution.
Are mostly solitary but do form groups during the colder months
Most hominids (but also monkeys or apes) are quite social, so this is a bit untypical - it could however be explained by other factors such as food availability in scotland (see above).
Have sloth like claws for digging up roots and peat
Most hominids/monkey/apes don't really have claws so this is, again, untypical. Elongated nails are fine, but real claws seem a bit much to me.
Have gorilla-like strength
Have very rudimentary tool use
Both of these are fine and in line with the species origin / similarity.