Bill Saxton wrote:
"...information >from the Lithuanian archives which identifies the given names of two of my ancestors as 'Iosel' where I have absolutely confirmed that their names were 'Hesel' - 'Gesel' in Russian. What is it about the original writing and/or translation of this name that causes this situation to occur so often?"

I have encountered a similar phenomenon, where the cursive Cyrillic letters in a handwritten document have been mistaken due to the lack of clarity in the handwriting. The cursive Cyrillic upper case "G" (or "gey") can look very similar to a "J" and a hastily-written lower case cursive "e" could be confused with "o". Thus, "Gesel" may have been read as "Josel" - Josel would be pronounced as "Yosel" which could then be transliterated as Iosel.

Lachaim,
Barry Spinak
Salisbury, MD, USA
Jewish Genealogy Society of Greater Washington
http://www.familytreemaker.com/users/s/p/i/Richard-B-Spinak/

Searching ... in Kovno Guberniya shtetls of Kraziai, Luoke, Plunge,
Tryskiai, Uzventis: FAYVUSH, FINKELSTEIN, GELIK, GELIL, GELIN, GERSH,
GIBER, HEILIG, HEILLIG, IOZEF, KALMAN, KAPLAN, KIL, MARKUS, NOKHUM,
RABINOWITZ, RAVID, RUBIN, SHAPIR, SHER, YAKUB, ZAMULIAN, ZIV
... >from Pogrebishche in Kiev Guberniya: KOTOVSKY
... >from Austria-Hungary: ROSENBERG
... >from Bohemia: GREEN, GRUEN, KLEINMAN, LEDERER, STEINER
... >from Warsawa: GOLDBERG, GOLDBRANDT, KATCHER, ROSENSWEIG, SPINAK
... and any Jewish families that ever lived in Pocomoke City, MD