Hi there Wormdiet.
Your solution to using both C’s, using your levers enharmonically, is completely viable. Don’t feel that you have to be hemmed in by one particular tuning, or technique because others use it. Explore different possiblities and find what works for you. Conformity is the opposite of creativity. Here’s some food for thought…
As blasphemous as this will sound to many, the unquestioned need for sharpening levers and lever changes has long baffled me as a harper. Useful as can be, they are not with their own set of woes. None of my harps have them, and I don’t miss them. Frequently there are better and more idiomatic solutions to be found. Talasiga’s useful idea of using other available notes ( ie. A fifth or other related notes) is well worth remembering; this has ample precedence in traditional music and older approaches to harping.
Similar issues face players of other traditional instruments. Pipes, whistles, keyless flutes have varying “limitations” chromatically and frequently resort to trickery to achieve or avoid accidentals. Some of their solutions to these problems are informative for we harpers.
Remember this too: If you aren’t playing with others you can often play tunes in another key. Other traditional musicians do this, I play D and A major tunes in C tuning all the time. Many the fluter and uilleann piper will play A and E major tunes in G or D to make them manageable on their instruments.
Some tunes do sound better with both forms of a note. One trick I’ve used to accommodate both C’s on wire harp with no levers, simply assign them to different octaves, with one C string being tuned natural and the other sharp. An octave might look like this from middle C: C# D E F G A B C natural. (You could reverse this too having the sharp c on the high string.) Breaking up the accidentals this way also helps avoid having a ringing minor second, and can be used with both F’s or both B’s. This could be just as easily achieved on nylon harp by retuning or using levers.
As Redwolf pointed out, there isn’t much call for flat keys in trad music. You can tackle just about anything with only tuning to C,G, and F. By tuning to G, due to the modal nature of most of the music, without levers, you can negotiate about 80 percent of Irish dance tunes, even playing with session with others. A large number of tunes that are written with two sharps, (particularly Dma, Emi dorian tunes) avoid the sharp seventh or use it sparingly. More often than not, you can skip these notes without anyone noticing. Take Morrison’s Jig for example. Most of the tune avoids the C# and you can play the whole tune just as well by replacing it with another note like B or D. Even more tunes are accessible by using the solutions mentioned above.
Have fun!!!
