Apparently all Japanese Reverse Holos of the Ultra Force (SM5+) set can come with both black text at the illustrator and set number, or white-outlined text. I learned this from someone on reddit.Here a random example:
The “Illus. match” and “003/050” texts are just black on the left card, but black with white outlines on the right card.
And here another one:
Looking at my own collection, it seems they’ve added the white-outlined texts for any Reverse Holo and Full Art cards for the second halve of the SM era and the entire SwSh era. Some examples of cards with the white-outlined illustrator and set number: the three Reverse Holo Detective Pikachu promos; the 400/SM-P Full Art promo; the Reverse Holos from the V Starter Sets; the Munch full art promos; etc.
I think that this SM5+ was the set on the turning point where they decided to add the white-outlined texts to Reverse Holo and Full Art cards from that point onward. So the ones with black text is a first print run, and the one with white outlined text a second print run. All sets prior to the SM5+ set have black texts, and all Reverse Holos and Full Art cards after the SM5+ set have white-outlined texts. (This only applies to Japanese cards; all other languages, including Korean Reverse Holos/Full Art cards, are with black texts only.)
Too bad the SM5+ set doesn’t contain a Pikachu nor Seviper, but a nice TIL moment regardless. 
EDIT: This apparently also applies to the SM1+ set.
Greetz,
Quuador