Here's a bit more on the T5. This is from a secret report on jungle weapons printed in November, 1943.
At that time it was expected 97,000 would be needed for the Pacific theater and 1000 had been produced and delivered in the U.S. Anticipated production for the following month, December, 1943, was 100,000 T5s. No idea how many more were actually produced before they shifted to the M19 but probably not too many. I assume the M9A1 warhead was used without the shape charge cone as the filler weight was listed at 8.5 ounces, the same as the standard M19 WP rifle grenade.
Another pub I have from 1945 refers to the M19 as the T5E1 with procurement in June of 1945 of 180,000 units with 50,000 a month through December.
Unfortunately, nothing more to add on the M34. I have something from the mid-1950s discussing the development of the E16R2 but, of course, can't find it in the pile.