only of the AC version was not compiled under the original name without ac extension
Assuming that jflpac works correctly with the name changed, and that the dll was built correctly, then I do not have any other ideas without trying 1.82, which is not going to happen soon.
However, if it is not working, then I would examine the above assumptions (if you have not already done so).
Name changes are usually, but not always, harmless.
I think that I remember that Adoxa posted header files on his web site. I do not know whether they are required for building jflp(ac). If the standard jflp(ac) works but your recompiled version does not, then check the headers.
Also, if you built your new jflp(ac).dll with a recent version of Visual Studio, then make sure that it is not built for a specific version of Windows. That could, potentially, cause the dll to work on some systems but not on others. It may be easier to build with older versions of Visual Studio (2005 or earlier) than it is with new versions.
This is Off Topic, but IMHO Microsoft's best software was the 2003 versions. Since then there have been more problems than there have been improvements. The only reason to use newer versions is for 64-bit support (which is important for big memory, unfortunately).
2003... that was a great year for Microsoft!