I found a German Lutheran version online. For context I include the preceding petition, and provide a translation:
"Treue Arbeiter in Deine Ernte senden,
Deinen Geist und Kraft zum Worte geben"
"Send true/loyal workers into Your harvest, Give Your Spirit and power to the word/message"
Based on this version and context, the Word is not Holy Scripture but the proclamation of the workers. This would be more consistent with Luther's understanding of proclamation, which is different from Holy Scripture, which he viewed as effective of itself (Isaiah 55:12). The preacher speaks for God and may rightly pray for His Spirit. Cf. Luther's version of the prayer/hymn, Come, Holy Spirit, God and Lord!
Here's where I found the text:
https://hymnary.org/hymn/EG1911/32