I have never heard of this brand of harp personally. I would consider these:
1) Do you have access to a string information chart? How easy it is to find replacement strings? Lever harp strings are often unique to each maker, especially the smaller harp manufacturers. I did a quick search and it doesn’t appear the Folkcarft are making harps these days. I would be really concerned about not able to buy replacement strings easily.
2) Which lever brand was used? What are the conditions of the levers? How easily can they be regulated? Levers have improved quite a bit in the last while. I don’t have a timeline, but an example would be the Camac levers: their current levers are way better than their first generation level. 1992 is not super long, but it is some time ago. If the levers were not working well or would require replacement, it could potentially be costly.
3) What’s the condition of the soundboard, neck, and column? How are the joints holding up? Those are some of the common places for structural failures on older lever harps. Not all problems would render the harp useless, but repair could be costly depending on the problem.
4) Is there a harp tech in your area who can check over the harp if you decided to go ahead with the purchase? It may cost you some money but it could be a worthwhile expense.