An issue was due to integers, placed in character buffer by yValve in wrong format.
In very many places of engine we do place integers in buffer in VAX format. But we never had common function to do it. Therefore - use of wrong for this purpose put_short and put_long. (Reverse function gds__vax_integer() existrs since beginning of FB time, and therefore no problems with backward conversion.)
I've added put_vax_short and put_vax_long and used them in yValve. Now it will be good idea to use them in all other places of our code base.