Identify tool that created FPGA files
The .abl extension is suggestive of the ABEL language, but I don't know whether that was ever used to program FPGAs. The Wikipedia page says that Xilinx now owns ABEL, so you could ask them whether it still supports Actel (kind of doubtful).

I worked extensively with Actel FPGAs in the 1990s, but we used Orcad schematic capture (not HDL) to design logic using Actel-supplied libraries, and then transferred the netlists into Actel's own toolchain for synthesis and programming.

I have some backup disks with the Actel software (as installed) on them, but I don't seem to have any original installation media. It's possible that their toolchain could parse ABEL source code directly, but I wouldn't know.