New in 8.1.28: Custom Touchscreen Keyboard Support

No, not currently. As a short term stopgap, you could go through windows in the designer and recursively apply the layout you want using adapted code from this post:

from com.inductiveautomation.vision.api.client.components.touchscreen import TouchscreenMouseListener

def getComponents(window):
	def walkComponents(component):
		for component in component.components:
			yield component
			walkComponents(component)
	
	return walkComponents(window.rootContainer)
	
isTouchscreenComponent = lambda component: isinstance(component, TouchscreenMouseListener)

def setKeyboardLayout(component, layout):
	component.keyboardName = layout

win = system.gui.getWindow("WindowName")
for component in filter(isTouchscreenComponent, getComponents(win)):
	setKeyboardLayout(component, "en_us_compat")