Remove the .end in the code block. Xschem will add a .end at the end of the netlist. I also don't see a command for a simulation, like tran and a save instruction (save all) You should have a .control block lke this:

.control
  save all
  tran 1n 300n
.endc

For a working example look into

sky130_tests/test_stdcells.sch

the example does work, but with an inverter made in .v it doesn't work. With sp.ys I get of file .xspice

compare your instance of

sky130_fd_sc_hd__clkinv_1

to the subckt-definition in

sky130_fd_sc_hd.spice

.

spi2xspice.py

already tries to tell you what's going on:

pin Y does not have a connecting net

Do you know how can I fix it?