"Error: String parameter 0 may not be used for gender queries {G ..}"

[absay]

Obligatory "sorry if not the right place to post".

There's a string: "STR_STATION_VIEW_RESERVED" that has to be translated to Spanish (Mexican) as follows:

{YELLOW}({CARGO_SHORT} reservad{G 0 o a}{P 0 "" s} para cargar)

The output in the game should be:

• 1 artículo reservado para cargar (male gender, singular)
• 2 artículos reservados para cargar (male gender, plural)
• 1 caja reservada para cargar (female gender, singular)
• 2 cajas reservadas para cargar (female gender, plural)

However, the tool complains with "Error: String parameter 0 may not be used for gender queries {G ..}". Changing the index parameter to "1" doesn't work either, and removing the gender syntax and leaving the plural one does work. What am I missing?

I already tried a similar syntax with "STR_TOWN_VIEW_CARGO_FOR_TOWNGROWTH_REQUIRED":

{ORANGE}{CARGO_TINY}/{CARGO_LONG}{RED} (todavía requerid{G 1 o a}{P 1 "" s})

And it came out without errors. I can sort of rephrase the translation as a workaround to avoid using genders in that specific string, but now I'm too obstinate to find out the issue here. Lol.

The documentation in the wiki is kind of confusing and seems incomplete, so I'd appreciate any help here. TIA.

edit: asked in Github, discussion here: https://github.com/OpenTTD/eints/issues/67