Simple tool to change the selected input source to named keyboard...

ChangeKeyboard.m

//
//  main.m
//  ChangeKeyboard
//
//  Created by Daniel Jalkut on 10/6/15.
//  Copyright © 2015 Red Sweater. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <Carbon/Carbon.h>

int main(int argc, const char * argv[]) {
	@autoreleasepool {
		if (argc < 2)
		{
			NSLog(@"Usage: %s <language>", argv[0]);
		}
		else
		{
			NSString* targetLanguage = [NSString stringWithUTF8String:argv[1]];
			TISInputSourceRef targetInputSource = NULL;
			for (id thisInputSource in (NSArray*)TISCreateInputSourceList(NULL, 0))
			{
				NSString* thisSourceName = (NSString*)TISGetInputSourceProperty((TISInputSourceRef)thisInputSource, kTISPropertyLocalizedName);
				if ([thisSourceName isEqualToString:targetLanguage])
				{
					targetInputSource = (TISInputSourceRef)thisInputSource;
					break;
				}
			}

			if (targetInputSource == NULL)
			{
				NSLog(@"Error: Could not find enabled input source matching language name: %@", targetLanguage);
			}
			else
			{
				TISSelectInputSource(targetInputSource);
			}
		}
	}
    return 0;
}