The first call you requested (as hinted before, this looks fine to me):
$ python3.8
Python 3.8.3 (default, May 14 2020, 22:09:32) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> "\t".join(['arith_int_512-cuda.sfeat', '__hipsyclkernel$wrapped_kernelname$MicroBenchArithmeticKernel_512_1', '578', '65', '5', '64', '4', '1025', '128', '1', '1', '512', '1'])
'arith_int_512-cuda.sfeat\t__hipsyclkernel$wrapped_kernelname$MicroBenchArithmeticKernel_512_1\t578\t65\t5\t64\t4\t1025\t128\t1\t1\t512\t1'


I can reproduce the issue on both:

Python 3.8.3 (default, May 14 2020, 22:09:32) 
[GCC 5.4.0 20160609] on linux

Python 3.6.6 (v3.6.6:4cf1f54eb7, Jun 26 2018, 19:50:54) 
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin


The second call you requested `echo 'arith_int_512-....'` will say 'command not found: arith_.....' in bash.