This is going to be a long preamble with background information on the Mbira family of instruments. I will post library-specific comments in a separate reply.
Unfortunately, there are no good Mbira libraries currently, unless the two listed above that I haven't gone into yet, turn out to be the exception:
- Versilian Studios - Versilian Community Sample Library
- Doru Malaia - 230 Ethnic Drums and Percussions
Terminology is still coalescing, but is quickly reaching consensus these past few years, but unfortunately quite a few sample libraries are mislabeled or misleading. It is unlikely that any of them sampled quality instruments played by knowledgeable players. I was rather horrified when I went through all of them yet again tonight, armed with ever-deeper knowledge that I have gained over the past few years.
The umbrella term is now considered to be Mbira, and Kalimba mostly just now refers to the modern chromatic single-row instruments initially popularized by High Tracey in the 1950's (I owned one of these in the 80's). Most westerners approach the more traditional instruments the same way, but they are played quite differently. Furthermore, instruments continue to involve, and thus there is a "traditional" non-chromatic variant that is NEWER than the Kalimba!
On top of all of that, there are special tunings, and also indigenous terms for the modes, that are sometimes applied to the instrument itself, but not always.
I had previously found all of the sources listed above, but this still left me with some confusion, all of which was resolved tonight after a lot of cross-referencing that led me to two specific resources that in conjunction with the main Wiki page for Mbira disambiguate most of the naming issues.
https://en.wikipedia.org/wiki/Mbira
https://en.wikipedia.org/wiki/Ikembe
https://kalimbashop.com/en/content/20-what-is-a-mbira
https://kalimbashop.com/en/content/19-what-is-a-kalimba
It would take too long to go into all of the regional naming differences, only some of which result in actual instrument design variants of any note. There is variation within each type anyway, but there are some broad generalizations that can be made.
In the Congo region (including Rwanda and Uganda), the main thumb piano is mostly now referred to as the Ikembe (or Likembe), and sometimes as Sanza (falling out of favour). Some of these have sound boxes, most are single-row, and they come in all sizes. Interestingly, this is the one that is closest in concept the the Hugh Tracey Kalimba -- his main innovation was to make it chromatic.
The Mbira originates mostly from Zimbabwe and Mozambique, and is a VERY different instrument as it is/was used almost exclusively in religious ceremonies and had specific adaptations that served a role in such activities. These instruments almost always have buzzers of some sort, tend to be large and in the tenor range. They also are usually played inside a large round calabash shell when used at ceremonies, to serve as natural amplification. Almost always, they have one hole in the lower right.
Things got a bit confusing though, when another instrument called the Mbira came into being in the 60's or 70's. This one borrowed some ideas from High Tracey's Kalimba, but steered clear of western chromatic tunings and tended to have duplication of notes in the upper register.
Mbiras are two-row designs, with the lower octave below, and the upper octave above. Some notes are played upwards vs. downwards, and by the index finger vs. the thumb. The sound can be fairly similar to other instruments in Africa that follow the wood-plus-metal-tine design basis, but the two-row concept seems to be fairly unique to the Zimbabwe region, along with the deeper range.
The older Mbiras that are mostly used for religious events, are generally referred to as Mbira Dvavadzimu, and the top row is split between left-side bass duties and right-side treble duties whilst the bottom row is only a half-row on the left for bass accompaniment to the right-hand treble.
The newer Mbiras are used more for social music, and have two full rows, as well as being more in the alto and soprano range, much smaller, only occasionally played inside a "deze" gourd shell, and tend to have some redundant symmetry along the top treble row of tines.
Most can be tuned for major/mixolydian modes or minor modes, and as the latter is less common, it is the one that is more often called out and sometimes used as the name of the instrument: Mavembe (as opposed to Nyamaropa, which rarely is even mentioned as it's the default).
This is all meant to be background information for people trying to figure out which instrument they actually want to model in their work, and also is meant to serve as a caveat that the label that you see for a library, or even a recording, may be incorrect, or at least misleading in terms of guiding you to the sound you're actually looking for.