When Spain claimed sovereignty over the area now known as Texas, they didn't actually have de facto control.

A big chunk of modern day residents of Texas trace their lineage back to waves of German and Czech migration. One large wave showed up in the 1830's and 1840's, negotiated a treaty with the Comanches who still controlled the land, and established German-speaking settlements through much of Central Texas. So actual control over the land was established by Germans more than it was Spanish.

Even in the portions of Texas conquered by Spanish settlers have now been settled by people who don't trace back to those Spaniards. The Spanish-speaking people of Texas declared independence with the rest of Mexico and became Mexicans. Then, after the war of Texas Independence, were mostly driven out by English-speaking Texians who had migrated from America (and largely trace back to to English, Scottish, or Irish migrants).

So no, modern day Texans are more German than they are Spanish. Just because the Spanish were the first to do it doesn't mean that they or their descendants actually held the land in the centuries that followed.

Uhhh, WISCONSIN!