如何在不同行的多个模式匹配后替换第n行的单词？

import re

def replace_word_in_nth_line(text, patterns, n, replacement):
    lines = text.split('\n')

    match_indexes = []
    for i in range(len(lines)):
        for pattern in patterns:
            if re.search(pattern, lines[i]):
                match_indexes.append(i)
                break

    if len(match_indexes) >= n:
        line_index = match_indexes[n-1]
        lines[line_index] = re.sub(r'\b\w+\b', replacement, lines[line_index])

    return '\n'.join(lines)

text = """
This is line 1.
This is line 2 with keyword.
This is line 3 with keyword.
This is line 4.
"""

patterns = ['keyword']
n = 2
replacement = 'replacement'

result = replace_word_in_nth_line(text, patterns, n, replacement)
print(result)

This is line 1.
This is line 2 with replacement.
This is line 3 with keyword.
This is line 4.